Risk factors in HIV-1-infected patients developing repetitive bacterial infections: toxicological,clinical, specific antibody class responses,opsonophagocytosis and Fc(gamma) RIIa polymorphism characteristics

The aim of the study was to determine possible factors related to the risk of developing recurrent bacterial respiratory tract infections in HIV-1-infected patients, regardless of the degree of immune cellular impairment. Thirty-three HIV-1 seropositive patients with previous repetitive bacterial respiratory tract infections (case group), 33 HIV-1 seropositive controls (matched by CD4-cell counts) without these antecedents and 27 healthy controls were studied before and after administration of pneumococcal and Haemophilus influenzae type b vaccines. Clinical or toxicological variables, cutaneous tests, complement factors, beta2-microglobulin, serum IgM, IgA, IgG and subclasses, specific antibodies (IgG, IgG2, IgA) against pneumococcal vaccine and polyribosylribitol phosphate (PRP), their avidity, opsonophagocytosis and IgG(2)m and Fc(gamma)RIIa allotypes were determined. A history of drug abuse (P = 0.001), less likelihood of receiving high activity antiretroviral treatment high activity antiretroviral treatment (HAART) (P = 0.01), higher levels of HIV-1 viral load (P < 0.05), serum IgG (P < 0.01) and beta2-microglobulin (P < 0.01) were observed in the case group. Also, a lower increase in specific antibodies to pneumococcal vaccine and PRP was demonstrated in the cases in comparison with the two control groups. No differences were observed in the avidity of antibodies, opsonophagocytic capacity or IgG(2)m and Fc(gamma)RIIa allotypes between the three groups. These data indicate that vaccination strategies against encapsulated bacteria can be unsuccessful in the HIV-1-infected patients presenting repetitive bacterial respiratory tract infections if behavioural aspects or measures to improve adherence to HAART therapies are not considered.     

Characterization of the translocated chromosome using fluorescencein situ hybridization and random amplified polymorphic DNA on twoTriticum aestivum—Thinopyrum intermedium translocation lines resistant to wheat streak mosaic or barley yellow dwarf virus

Fluorescencein situ hybridization (FISH) was used to determine the breakpoint of the translocation chromosome in two bread wheat (Triticum aestivum) germplasm lines withThinopyrum intermedium chromatin carrying resistance to either wheat streak mosaic virus (WSMV) or barley yellow dwarf virus (BYDV). In addition, genome-specific random amplified polymorphic DNA (RAPD) markers were used to ascertain the genomic sources of theTh. intermedium chromosomes carrying the WSMV or BYDV resistance. CI17766, a WSMV-resistant wheat germplasm line derived from induced homoeologous pairing by using theph1b mutant, had a translocation chromosome composed of the complete 4AL and about 45% of proximal 4AS from wheat, and the entire 4ES ofTh. intermedium. The BYDV-resistant translocation line, TC14, derived from tissue culture, had a very short distal segment of 7StL fromTh. intermedium terminally attached to 56% of the proximal 7DL. These observations indicate that translocations in these wheat germplasm lines did not involve centromeric breaks and fusion but were a result of homoeologous chromosome recombination.accepted for publication by J. S. (Pat) Heslop-Harrison     

Characterisation of macrolide-non-susceptible Streptococcus pneumoniae colonising children attending day-care centres in Athens, Greece during 2000 and 2003

Nasopharyngeal Streptococcus pneumoniae isolates colonising young children are representative of isolates causing clinical disease. This study determined the frequency of macrolide-non-susceptible pneumococci, as well as their phenotypic and genotypic characteristics, among pneumococci collected during two cross-sectional surveillance studies of the nasopharynx of 2847 children attending day-care centres in the Athens metropolitan area during 2000 and 2003. In total, 227 macrolide-non-susceptible pneumococcal isolates were studied. Increases in macrolide non-susceptibility, from 23% to 30.3% (p <0.05), and in macrolide and penicillin co-resistance, from 3.4% to 48.6% (p <0.001), were identified during the study period. The M resistance phenotype, associated with the presence of the mef(A)/(E) gene, predominated in both surveys, and isolates carrying both mef(A)/(E) and erm(AM) were identified, for the first time in Greece, among the isolates from the 2003 survey. Pulsed-field gel electrophoresis analysis of the isolates from the 2000 survey indicated the spread of a macrolide- and penicillin-resistant clone among day-care centres. The serogroups identified most commonly in the study were 19F, 6A, 6B, 14 and 23F, suggesting that the theoretical protection of the seven-valent conjugate vaccine against macrolide-non-susceptible isolates was c. 85% during both study periods.     

Electrolyte Medium Effects on Measurements of Palmar Skin Potential

Two experiments with 12 subjects each compared skin potential recordings taken simultaneously with four different electrolytes. These were polyethylene glycol, hydrated agar (at a site presoaked with water), fresh agar (i.e., not presoaked), and Unibase. The glycol controlled epidermal hydration at a minimal level, while presoaking produced a high level of hydration at the hydrated agar site. Fresh agar and Unibase represented normal recording conditions for these two electrolytes which have been recommended as “standard” for electrodermal measurements. This design permitted a comparison of two standard electrolytes with each other and with recordings from hydrated and unhydrated sites. These comparisons were made for both monophasic negative SPRs and positive SPRs and the prestimulus levels associated with each. The results replicated previous studies in showing a large effect of epidermal hydration on skin potential measurements. Recordings with agar and Unibase did not differ significantly. The effects of hydration were interpreted in terms of a reduction in the resistance of the stratum corneum and of alterations in the functioning of the dermal and epidermal membranes as a result of blockage of the sweat gland pore. In the light of this interpretation, it was suggested that both agar and Unibase substantially alter the functioning of the sweat glands under some conditions, and neither may be entirely suitable for skin potential measurements.     

The reflex effect of changes in renal perfusion on hindlimb vascular resistance in anaesthetized rabbits

This study was designed to characterise the response of the hindlimb vasculature to reduced renal perfusion in the anaesthetized rabbit and to elucidate whether the stimulus was dependent upon reduced renal perfusion pressure (RPP) or blood flow (RBF). Acute decreases in renal perfusion resulted in rapid and reversible increases in femoral perfusion (FPP). This vascular response was completely abolished following renal denervation indicating that the afferent component of the reflex is neurally mediated. Acute hindlimb responses to changes in renal perfusion pressure were present whether the limb was perfused with homologous blood or cross-perfused with blood from a donor rabbit, demonstrating that the efferent component of the response is also neurally mediated. There was a 28-s latency for initiation of the hindlimb vasoconstriction, which is consistent with recent evidence for renal autocoid stimulation of the afferent renal nerve receptors. Decreasing RPP indirectly, by altering flow, resulted in a hindlimb vasoconstriction below approximately 55 mm Hg (7.3 kPa) RPP or 15 ml/ min RBF. However, decreasing RPP by directly reducing pressure in graded steps resulted in increases in FPP, which reflected the changes in renal flow; thus during the autoregulatory phase, where flow did not change as pressure fell, FPP also remained stable. The results of these protocols suggest that a neurally mediated hindlimb vascular reflex is stimulated by decreased renal flow rather than pressure.     

Effect of human serum on bioluminescence of natural and recombinant luminescent bacteria

Biphasic modification of bacterial bioluminescence by human serum was revealed: bioluminescence was inhibited at high concentrations of the serum and stimulated at low concentrations. Effects of temperature and duration of exposure on bioluminescence manifested in stimulation of the inhibitory effect at higher temperature and longer exposure. The degree of inhibition of bioluminescence under in the presence of serum depends on species characteristics of the microorganism and nature of the luminescent system. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 9, pp. 311–315, September, 2004     

Molecular epidemiology of penicillin-resistant Streptococcus pneumoniae in a university hospital, Ankara, Turkey

Penicillin-resistant Streptococcus pneumoniae isolates (n = 76) from clinical samples of patients admitted to Hacettepe University Hospital between January 1997 and December 2001 were included in the study. MICs of penicillin G, erythromycin A, clindamycin, cefaclor, cefotaxime, vancomycin, chloramphenicol, tetracycline, ciprofloxacin and rifampicin were determined by agar dilution. The isolates were serogrouped on the basis of the Neufeld Quellung reaction and were typed by BOX-PCR. Genetic polymorphism of the penicillin resistance genes pbp2b and pbp2x was investigated by restriction fragment length polymorphism (RFLP) analysis. Of the 76 isolates tested, 64 (84.2%) showed intermediate resistance to penicillin, while 12 (15.8%) were resistant to higher levels of penicillin (MIC > or = 2 mg/L). The resistance patterns of the isolates revealed six different resistance profiles. There were 22 different serotypes, with c. 55% of the isolates belonging to serotypes 23B, 19A, 19F, 14, 6 A and 9V. Five distinct patterns for pbp2b and 12 distinct patterns for pbp2x were obtained by RFLP analysis of penicillin-binding protein genes. The combination of these patterns allowed isolates to be classified into 22 fingerprint subgroups. BOX-PCR analysis showed that the isolates fell into 14 distinct BOX genotypes, with 33 subtypes. Serotype 9V isolates with pbp genotype 2-6 and BOX-PCR type 4, 4.1 or 4.2 were related to the pandemic clone Spain(9V)-3. No relatedness to other international clones was detected among the other study strains, but genetic relatedness was observed among some of the serotype 19A and 23B isolates. Overall, the results demonstrated that most of the penicillin-resistant pneumococcal isolates in Turkey, other than those belonging to serotypes 9V, 19A and 23B, were derived from several independent clones, possibly resulting from multiple importation of strains originating from outside the country. Differences in pbp patterns, serotypes and resistance profiles among isolates that showed similar BOX-PCR patterns supported the hypothesis that horizontal transfer of capsular genes, pbp genes and other genetic determinants between S. pneumoniae and viridans group streptococci may have occurred.     

Methylation and Expression of FTO and PLAG1 Genes in Childhood Obesity: Insight into Anthropometric Parameters and Glucose–Lipid Metabolism

The occurrence of childhood obesity is influenced by both genetic and epigenetic factors. FTO (FTO alpha-ketoglutarate dependent dioxygenase) is a gene of well-established connection with adiposity, while a protooncogene PLAG1 (PLAG1 zinc finger) has been only recently linked to this condition. We performed a cross-sectional study on a cohort of 16 obese (aged 6.6–17.7) and 10 healthy (aged 11.4–16.9) children. The aim was to evaluate the relationship between methylation and expression of the aforementioned genes and the presence of obesity as well as alterations in anthropometric measurements (including waist circumference (WC), body fat (BF_kg) and body fat percent (BF_%)), metabolic parameters (lipid profile, blood glucose and insulin levels, presence of insulin resistance) and blood pressure. Expression and methylation were measured in peripheral blood mononuclear cells using a microarray technique and a method based on restriction enzymes, respectively. Multiple regression models were constructed to adjust for the possible influence of age and sex on the investigated associations. We showed significantly increased expression of the FTO gene in obese children and in patients with documented insulin resistance. Higher FTO expression was also associated with an increase in WC, BF_kg, and BF_% as well as higher fasting concentration of free fatty acids (FFA). FTO methylation correlated positively with WC and BF_kg. Increase in PLAG1 expression was associated with higher BF%. Our results indicate that the FTO gene is likely to play an important role in the development of childhood adiposity together with coexisting impairment of glucose-lipid metabolism.