O-O bond cleavage via electrochemical reduction of a side-on peroxo dicopper model of hemocyanin.

The redox properties of the µ-η2:η2 peroxo complex [Cu2(H6M4h)(O2)]2+ were elucidated. This study constitutes the first full electrochemical and spectroelectrochemical characterization of a side-on peroxo Cu2:O2 bioinorganic model complex. The peroxo complex is irreversibly reduced in a two-electron process localized on the peroxo ligand triggering the cleavage of the O-O bond.

Prevalence of infection in ticks submitted to the human tick test kit program of the U.S. Army Center for Health Promotion and Preventive Medicine.

In 1997, ticks removed from humans and received alive by the Tick-Borne Disease Laboratory of the U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM) were tested for pathogens by polymerase chain reaction (PCR). Thirty-three of 222 (15%) Amblyomma americanum (L.) DNAs produced amplicons of the expected size of Ehrlichia chaffeensis Anderson, Dawson & Wilson and 26/222 (12%) produced amplicons indicating Borrelia burgdorferi Johnson, Schmid, Hyde, Steigalt & Brenner. Five (2%) appeared to be co-infected with both organisms. Thirteen of 308 (4%) Dermacentor variabilis (Say) were PCR-positive for spotted fever group rickettsiae. Restriction fragment-length polymorphism analysis indicated all were Rickettsia montana. One hundred twenty-seven D. variabilis from Monroe County, WI, were tested for B. burgdorferi and 14 (11%) were positive. Five of 24 (21%) Ixodes scapularis Say were positive for B. burgdorferi and one (2%) was positive for the agent of human granulocytic ehrlichiosis. Different species of ticks transmit different pathogens, and most tick-borne diseases have similar early symptoms, therefore knowing the species and infection status of the tick enhances the physician's ability to consider tick-borne agents as a potential cause of disease and recommend appropriate therapy. Ongoing surveillance of the vector species of human diseases provides an additional estimate of human encounters with infected ticks, and testing ticks removed from humans may increase our knowledge of the vector status of tick species for transmitting tick-borne pathogens.

Ehrlichia chaffeensis (Rickettsiales: Ehrlichieae) infection in Amblyomma americanum (Acari: Ixodidae) at Aberdeen Proving Ground, Maryland.

Human monocytic ehrlichiosis (HME) is a sometimes fatal, emerging tick-borne disease caused by the bacterium Ehrlichia chaffeensis. It is frequently misdiagnosed because its symptoms mimic those of the flu. Current evidence indicates that Amblyomma americanum (L.), the lone star tick, is the major vector of HME. To determine if E. chaffeensis is present in ticks at Aberdeen Proving Ground, MD, questing A. americanum ticks were collected from 33 sites. Nucleic acid was extracted from 34 adult and 81 nymphal pools. Sequences diagnostic for E. chaffeensis from three different loci (16S rRNA, 120-kDa protein, and a variable-length polymerase chain reaction [PCR] target, or VLPT) were targeted for amplification by the PCR. Fifty-two percent of the collection sites yielded pools infected with E. chaffeensis, confirming the presence and widespread distribution of E. chaffeensis at Aberdeen Proving Ground. Analysis with the both the 120-kDa protein primers and the VLPT primers showed that genetic variance exists. A novel combination of variance for the two loci was detected in two tick pools. The pathogenic implications of genetic variation in E. chaffeensis are as yet unknown.

Detection of the agents of human ehrlichioses in ixodid ticks from California.

A study was conducted in northern California to estimate the prevalence and distribution in ixodid ticks of the rickettsial agents of human monocytic (HME) and human granulocytic (HGE) ehrlichioses. More than 650 ixodid ticks were collected from 17 sites in six California counties over a 15-month period. Ehrlichia chaffeensis, the causative agent of HME, was detected by a nested polymerase chain reaction (PCR) in Ixodes pacificus (minimum infection rate [MIR] = 13.3%) and Dermacentor variabilis (infection rate=20.0%) from a municipal park in Santa Cruz County. The HGE agent was detected by nested PCR in I. pacificus adults from a heavily used recreational area in Alameda County (MIR = 4.7%) and a semirural community in Sonoma County (MIR = 6.7%). Evidence of infection with Ehrlichia spp. was not detected in D. occidentalis adults or I. pacificus nymphs. This study represents the first detection of E. chaffeensis in California ticks and the first report of infection in Ixodes spp. The competency of I. pacificus to be coinfected with and to transmit multiple disease agents, including those of human ehrlichioses and Lyme disease, has yet to be determined.

Quantitative evaluation of hepatitis C virus RNA in patients with concurrent human immunodeficiency virus infections.

Quantitation of the hepatitis C virus (HCV) provides a powerful epidemiologic and therapeutic method for the evaluation of infected patients. In this study semiquantitative reverse transcriptase polymerase chain reaction (PCR) is compared with a new branched DNA signal amplification methodology. Samples from HCV-infected patients as well as from human immunodeficiency virus-infected patients were evaluated. Reverse transcriptase PCR correlated well with the branched DNA assay (r = 0.7036, P < 0.05). HCV RNA was found to occur at significantly higher titers (P < 0.05) in patients coinfected with the human immunodeficiency virus compared with titers in those infected with HCV alone. Immune status as defined by the CD4+ count was not associated with the observed difference in viral titer.

[Mycoplasma sp. in the respiratory tract of hospitalized children]. / Investigación de Mycoplasma sp. en las vías respiratorias de niños hospitalizados.

Mycoplasma pneumoniae is one of the most common bacteria causing respiratory diseases in other countries, specially in older children, adolescents and young adults and less frequently in the age group studied here, nevertheless the determination of its presence in this group was considered important. Two hundred and fifty throat swabs were taken from children, under five years of age, hospitalized with a diagnosis of acute respiratory infections (ARI) and to 50 children, same age, with no ARI (controls). The samples were placed in transport media and were incubated at 37 degrees C during 7 to 15 days. They were reinoculated in PPLO agar and typical colonies were looked for, 5 to 8 days later. The organisms were identified by biochemical tests. Eight Mycoplasma sp (3.2%) were obtained, five of them were M. pneumoniae (2.0%) and three M. hominis (1.2%). Only in 2 cases adenoviruses with M. hominis were found in the absence of other pathogens. It was shown that M. pneumoniae also infects children under five years old, so its present should be suspected, specially when the patient's health does not improve with the installed treatment. Some important suggestions for the isolation of mycoplasma are given.

Cloning and dosage compensation of the 6-phosphogluconate dehydrogenase gene (Pgd+) of Drosophila melanogaster.

Using a heterologous rat cDNA probe, we have identified a 14.7 kbp Drosophila melanogaster genomic clone containing the X-linked gene Pgd+, which encodes the enzyme 6-phosphogluconate dehydrogenase (6PGD). We used in situ hybridization to larval polytene chromosomes, a somatic transient expression assay for enzyme activity, and the rescue of the lethal Pgd- phenotype by germline transformation to verify the identity of the gene. A 7.4 kbp fragment including the gene and approximately 1.2 kbp of upstream and 1.8 kbp of downstream sequences was relocated to autosomal ectopic sites by germline transformation; this transduced gene exhibits levels of enhanced activity in males comparable to those of the indigenous gene at its normal X chromosome locus. We conclude that the sequences responsible for dosage compensation of Pgd+ are included in this fragment.

Nucleotide sequence of the Drosophila glucose-6-phosphate dehydrogenase gene and comparison with the homologous human gene.

Glucose-6-phosphate dehydrogenase (G6PD) has a major role in NADPH production and is found in almost all cell types. The structural gene for G6PD is X-linked in Drosophila melanogaster, as it is in most eukaryotic organisms, and due to its ubiquitous expression, it can be considered a typical 'housekeeping' gene. Here we present the complete nucleotide (nt) sequence of G6PD cDNAs as well as the genomic copy of the G6PD gene. The G6PD gene has three introns so that the protein-coding region is divided into four segments. The 5'-end of mature G6PD mRNA is located 289 +/- 1 nt upstream from the start codon. The sequence upstream from the transcription start point is G + T-rich and contains no commonly found transcription regulatory elements, such as a TATA box or GGGCGG sequence. D. melanogaster G6PD is 65% homologous with the human G6PD protein but has no homology with the human sequence for the first 42 amino acid residues. The G6PD gene was shown to be active when transduced to autosomal positions. For each transformant, G6PD activity in both male and female adults was not significantly different, indicating that the transduced gene, unlike the resident G6PD, is not dosage-compensated in males.

Toupet's valvuloplasty for sliding hiatal hernia and incompetent inferior esophageal sphincter.

The experience obtained in 90 consecutive Toupet's valvuloplasties performed at the General Surgery Service of the "Calixto Garcia" University Hospital is presented. Indications for the operation were a sliding hiatal hernia in 87 patients and an incompetent inferior esophageal sphincter in 3 patients. The time elapsed after operation ranged from 1 to 9 years in 80 patients who could be followed up (88.9% of the casuistic).--There was no mortality directly related with the surgical procedure, 95% of the patients improved their symptoms and in 85% of them there were no symptoms dependent of the valvuloplasty performed.