Systemic infections in three infants due to a lactose-fermenting strain ofSalmonella virchow

Three previously healthy children developed gastroenteritis which led within a few days to systemic infections, two cases of bacteremia and one of meningitis. A lactose-fermentingSalmonella virchow strain was isolated from cerebrospinal fluid and blood cultures. In one case, this strain was also isolated from stool cultures. All the children had been fed the same milk formula. There was no other relationship between them. The batch of dried-milk formula was confirmed as the source of the infection by isolation of an identical lactose-fermentingSalmonella virchow strain by the Centro Nacional de Alimentación.     

Lack of correlation between impaired Interferon production and natural killer activity of lymphocytes in multiple sclerosis

Summary The ability of lymphocytes from patients with multiple sclerosis (MS) to produce Interferon (IFN-) in response to Newcastle Disease Virus (NDV) was studiedin vitro. The correlation between individual IFN- titers and natural killer (NK) cell activity and the presence of HLA system antigens associated with MS (B-7 and DRW-2) was also investigated.Lymphocytes from MS patients showed a significantly impaired capacity to synthesize IFN-in vitro when compared to lymphocytes from healthy donors (mean titers: 85.9 I.U. and 268.2 I.U., respectively). Marked differences in IFN- titers were observed in the group of MS patients.The production of IFN- by the patients' lymphocytes did not correlate with either the activity of NK cells or with their stimulation by exogenous IFN-. There was also no correlation between IFN- production by lymphocytes from MS patients and the presence or absence of B-7 and DRW-2 antigens.With 3 Figures     

Synergistic effect of azithromycin on the phagocytic killing ofStaphylococcus aureus by human polymorphonuclear leukocytes

Many macrolides have been shown to affect the interaction between bacteria and various immune defense mechanisms, such as chemotaxis, accumulation, and bioactivity within phagocytic cells. The interaction of azithromycin with human polymorphonuclear leukocytes (PMNs) was studied in vitro and compared with the interactions between other macrolides and PMNs. The opsonophagocytic killing ofStaphylococcus aureus was synergistically enhanced by azithromycin at concentrations below and above the minimal inhibitory concentration, with a reduction of up to 2.82 log₁₀ cfu/ml with 2 mg/ml of azithromycin. Other macrolides were effective only at subinhibitory concentrations. The beneficial azithromycin-leukocyte interaction may explain azithromycin's efficacy against intracellular pathogens.     

Analysis of the Equalization of Inverted Repeats and Neurovirulence Using a Pseudorabies Virus Mutant Strain Altered at the Ul/Ir Junction

A recombinant pseudorabies (Aujeszky’s disease) virus (PrV) designated as vE16lac was constructed by deleting a 3-kbp DNA segment spanning the junction of long and short components of the viral genome, and by replacing the deleted segment with a lacZ-expression cassette. The aim of constructing this mutant was (a) to determine whether the terminal repeat (Tr) can serve as a template for the regeneration of the internal repeat (Ir), and (b) whether this deletion causes a reduction in the neuroinvasiveness of the virus. To analyze the mechanism of equalization, revertant viruses were selected and structurally characterized from vE16lac infection of PK-15 cells, mice and pigs. Because all revertants acquired Ir sequences identical to that of the wild-type virus, the equalization process occurred using the Tr as a template to reconstitute the Ir. We also found that the recombinant virus vE16lac was virulent in both pigs and mice. The data are discussed in view of studies performed with similar PrV mutants by other authors (Rall et al., 1992, Dean and Cheung, 1995 and Dean et al., 1996). This revised version was published online in July 2006 with corrections to the Cover Date.     

The experimental receptivity ofHelicella (Helicella) itala andCepaea nemoralis (Mollusca,Helicidae) to larvae ofMuellerius sp. andNeostrongylus linearis (Nematoda,Protostrongylidae) from chamois (Rupicapra rupicapra)

Two batches ofHelicella (H.) itala (adult specimens) and two ofCepaea nemoralis (adult and young specimens) were experimentally infected with larvae I (L-I) ofMuellerius sp. andNeostrongylus linearis obtained from the lungs and faeces ofRupicapra rupicapra. In assess larval development, the number and percentage of the total number of larvae (L-I+L-II+L-III) per mollusc were studied, together with the number and percentage of L-III per snail and the days on which the different larval stages were reached. The development ofMuellerius sp. andN. linearis was greater in larvae from faeces. For both species of molluscs, the values for the percentages of the total number of larvae and L-III were higher inN. linearis than inMuellerius sp., but there were no notable differences in the days on which the various larval stages were reached. Both nematodes achieved a greater degree of development in young specimens ofC. nemoralis than in adults. Whether the larvae came from facces or the lungs,H. (H.) itala was a better intermediate host thanC. nemoralis forMuellerius sp. andN. linearis.     

Evaluation of the mutagenic and cytotoxic effects of mercurous chloride by the micronuclei technique in golden Syrian hamsters

The aims of this study were to evaluate the mutagenic and cytotoxic activity of mercurous chloride by the micronucleus technique in vivo on the bone marrow of golden Syrian hamsters after a single i.p. drug administration. Forty male golden Syrian hamsters were classified into eight groups: negative control, positive control and six groups treated with different doses of mercurous chloride (1.25, 2.5, 5, 10, 20 and 40 mg/kg). The negative control was injected with physiological saline i.p. and the positive control with cyclophosphamide at a dose of 80 mg/kg i.p. With respect to mutagenic effect, the average number of micronucleated polychromatic erythrocytes (MPE) in hamsters treated with different doses of mercurous chloride was not significant compared with the negative control. With respect to cytotoxic effect, the average polychromatic erythrocyte/red blood cell ratio showed a significant decrease when the doses were higher than the 2.5 mg/kg dose compared with the negative control. In conclusion, this preliminary study shows a cytotoxic effect but not a mutagenic effect of calomel in vivo at one time point (24 h).     

Heat-shock protein (HSP70-2) allelic frequencies in three distinct Mexican populations

The major histocompatibility complex (MHC) genes are highly polymorphic and therefore have been useful in population genetics and disease association studies. We analyzed restriction fragment length polymorphism of HSP70-2 alleles in healthy unrelated Mestizo, Mazatecan and Nahua populations. Both Indian groups, Mazatecans and Nahuas, were in Hardy-Weinberg equilibrium, while Mestizos were in disequilibrium (chi 2 = 0.399; P < 0.05). The Mazatecan Indians presented a high frequency of BB homozygosity (17.35%) compared to Mestizos (5%) (P = 0.01). Mexican ethnic groups present differences in distribution of BB genotype. The low frequency of BB genotype in Mestizos may be the result of a negative selection process.