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Biomedical subjects

D Nadal

Publications and source records attributed to D Nadal.

At least 37 records · Page 2Linked to original sources
PubMed2000

Rapid detection of Mycoplasma pneumoniae in clinical samples by real-time PCR.

M. pneumoniae is a common causative agent of community-acquired pneumonia in children. The diagnosis of such infections is usually based on serology using complement fixation or, more recently, enzyme-immuno assays. PCR has been shown to be a promising alternative. We have evaluated a real-time PCR assay targeting the P1 adhesion protein gene and compared it to a conventional semi-nested PCR assay with the 16S rDNA as target. Comparison of 147 specimens from 48 patients showed an overall agreement of 97.4%. Real-time PCR proved to be of equal value on clinical specimens as conventional PCR regarding sensitivity and specificity, but is clearly advantageous regarding speed, handling and number of samples that can be analyzed per run.

Adolescent↗
PubMed2000

A toddler with burns, stomatitis, and skin graft loss.

The authors report on a healthy 21-month-old toddler with 13% TBSA deep scald burns who was successfully grafted (take 100%). In the immediate postoperative phase, the patient developed classical aphthous stomatitis and subsequent herpes viremia leading to severe viral "graftitis". Although immediately administered intravenous acyclovir therapy appeared to be effective, one third of grafts were lost and had to be replaced. The lesson from this case is 2-fold: Herpes infection may threaten even perfectly engrafted fresh skin transplants, and, freshly grafted or soon to be grafted burn patients should be given intravenous antiviral therapy as soon as a herpes infection is diagnosed.

Antiviral Agents↗
PubMed2000

Use of HIV-1 p24 as a sensitive, precise and inexpensive marker for infection, disease progression and treatment failure.

HIV RNA is an acknowledged marker of disease activity and predictive of progression, while the p24 antigen is considered unsuitable. This is at odds with the fact that viral pathogenesis is usually mediated by proteins. One might expect that p24, if analyzed properly, might even be superior to RNA. This hypothesis was investigated in clinical studies using a sensitive and precise p24 test (heat-mediated immune complex dissociation with signal amplification-boosted ELISA). This test was as sensitive and specific as the polymerase chain reaction (PCR) for viral RNA (200-400 copy detection), an overall better predictor of CD4 decline and survival, while RNA prevailed in predicting AIDS. The lower costs of p24 testing also permit a closer monitoring of patients with an earlier detection of anti-retroviral treatment failures.

Biomarkers↗
PubMed1999

Sequence polymorphisms between latent membrane proteins LMP1 and LMP2A do not correlate in EBV-associated reactive and malignant lympho-proliferations.

The latent membrane proteins LMP1 and LMP2A are co-expressed in most malignancies associated with Epstein-Barr virus (EBV). In contrast with the transforming LMP1 oncoprotein, LMP2A is expressed in lymphocytes of healthy EBV carriers and considered to maintain viral latency. Critical for these LMP2A functions are a transmembranous epitope recognized by specific cytotoxic T lymphocytes (CTLs) and the N-terminal immunoreceptor tyrosine-based activation motif (ITAM), blocking B-cell receptor signaling. To characterize ITAM and CTL motifs of LMP2A and to correlate them with C-terminal variants of LMP1 including the 30-bp deletion variant (LMP1delta), comparative sequence analysis was performed on 76 samples from patients with reactive and malignant lympho-proliferation (infectious mononucleosis, n=21; tonsillar hyperplasia, n=16, chronic lympho-proliferation, n = 9; Hodgkin's disease, n = 8; Non-Hodgkin's lymphoma, n = 5; AIDS-related large-cell lymphoma, n=17). The CTL motif was conserved in all but 2 cases (C426-->S). The ITAM motif was characterized by strictly conserved YXXL sequences in all cases, with a sequence polymorphism in between. The B95.8 prototype was found in 17% (13/76) of cases, while in 72% a variant with 3 point mutations (166796 C-->A, 166805 C-->A, 166810 C-->T) was detected; 11% had 1 or 2 of these mutations in addition to G-->A at 166793. In the C terminus of LMP1, a hypervariable region including LMP1delta was described in 61% of cases. There was no significant association of a particular LMP2A variant with either malignant phenotype or LMP1delta, demonstrating that the functional domains of LMP2A are conserved and that the sequence polymorphisms in LMP1 and LMP2A are independent.

Conserved Sequence↗
PubMed1999

Hepatic steatosis: a frequent non-specific finding in HIV-infected children.

Thirty HIV-infected children were cross-sectionally examined for morphologic hepatic abnormalities, using ultrasonography or histology. Abdominal ultrasonography was performed in 27 children. The liver structure was normal in four patients, one of whom had moderate symptoms of the HIV infection and three of them severe symptoms. Abnormal liver structure, compatible with hepatic steatosis, was found in 23 (85%) patients. Five of them were in an early stage of the HIV infection (category N or A), three patients were ranked in category B and 15 patients in category C. Histological examination of the liver was performed in 11 children and steatosis was documented in ten (91%). In seven (70%) of these ten children steatosis had been suspected by ultrasonography. In conclusion, steatosis is common in HIV-infected children. It is non-specific and has no impact on disease, diagnostic evaluation or management. Conclusion Ultrasonography is a sensitive, accurate, non-invasive screening tool. It is more reliable than liver function tests.

Adolescent↗
PubMed1999

Detection and quantification of cell-free Epstein-Barr virus by polymerase chain reaction and subsequent DNA enzyme immunoassay.

Amplification by polymerase chain reaction and subsequent DNA enzyme immunoassay (DEIA) were employed to determine the number of genome equivalents of cell-free Epstein Barr virus (EBV) DNA in peripheral blood. The assay detected cell-free EBV DNA in the serum of 14 out of 18 patients with primary, productive EBV infection (sensitivity 77.7%) but not in healthy EBV carriers with latent infection (specificity 100%). Our assay has the potential for a clinical diagnostic tool to monitor patients at risk for EBV reactivation and productive infection with subsequent EBV-induced lymphoproliferative diseases.

Base Sequence↗
PubMed1999

False-positive beta-lactamase results with Staphylococcus lugdunensis in the Vitek AutoMicrobic system.

The Vitek AutoMicrobic system in combination with the Gram-positive susceptibility card detects beta-lactamase in staphylococci by utilizing penicillin as the substrate coupled with oxacillin as an inducer. The beta-lactamase activity of 21 clinical isolates and two reference strains of Staphylococcus lugdunensis was determined with this automated system and compared with a liquid nitrocefin assay after induction with oxacillin. Eight (38%) clinical isolates and the reference strain ATCC 49576 of S. lugdunensis showed production of beta-lactamase in both tests. Thirteen (62%) clinical isolates and the type strain ATCC 43809 were nitrocefin-negative. The Vitek AutoMicrobic system reported false-positive beta-lactamase results for 9 of those 13 isolates and for the type strain of S. lugdunensis. Results for disk diffusion (ampicillin) were concordant with the nitrocefin assay. With one exception, the MICs for penicillin of the nitrocefin-negative strains were in the equivocal range of 0.06-0.12 mg/l according to NCCLS. However, none of the nitrocefin-negative and Vitek-positive strains revealed any of the known staphylococcal genes for beta-lactamase as investigated by Southern hybridization, supporting the fact that false-positive beta-lactamase results may occur in the Vitek AutoMicrobic system. We conclude from our data that it may be justified to include S. lugdunensis in the quality control of Vitek cards containing beta-lactamase tests.

Diffusion↗
PubMed1999

[Vaccinations].

Vaccines are amongst the most cost effective interventions in medicine. Optimal implementation of actually available vaccines would markedly increase the enormous benefits for mankind achieved so far. Biotechnology has allowed improvement of old and engineering of new vaccines. However, there is still urgent need for vaccines against pathogens with a global morbidity and mortality toll. The challenges for the 21st century to close the increasing gap between developed and developing countries are bound to biology, finances, cooperation and solidarity.

Communicable Disease Control↗
PubMed1999

Prospective evaluation of amplification-boosted ELISA for heat-denatured p24 antigen for diagnosis and monitoring of pediatric human immunodeficiency virus type 1 infection.

The performance in pediatric human immunodeficiency virus type 1 (HIV-1) infection of a signal-amplification boosted ELISA for HIV-1 p24 antigen in plasma after heat-mediated immune complex dissociation was prospectively compared with polymerase chain reaction-based procedures. Diagnostic sensitivity and specificity of the p24 antigen test were 100% and 99.2%, respectively. Quantification revealed RNA in 85.7% and p24 antigen in 87.4% of 230 samples from 25 infected children. Concentrations of these indices in individual samples correlated (P<.0001). Introduction or modification of antiretroviral treatment showed concordant responses of RNA and p24 antigen in 39 (90.7%) of 43 instances. The treatment-induced changes in concentrations of RNA were higher than those of p24 antigen in 11 instances. In 1 instance, however, the concentration change of p24 antigen was greater than that of RNA (P=. 002). Variation of RNA concentrations was more marked than that of p24 antigen (P=.002). The p24 antigen test was equivalent to PCR for diagnosing and monitoring pediatric HIV-1 infection.

Anti-HIV Agents↗
PubMed1999

Analysis and dynamics of the chromosomal complements of wild sparkling-wine yeast strains.

We isolated Saccharomyces cerevisiae yeast strains that are able to carry out the second fermentation of sparkling wine from spontaneously fermenting musts in El Penedès (Spain) by specifically designed selection protocols. All of them (26 strains) showed one of two very similar mitochondrial DNA (mtDNA) restriction patterns, whereas their karyotypes differed. These strains showed high rates of karyotype instability, which were dependent on both the medium and the strain, during vegetative growth. In all cases, the mtDNA restriction pattern was conserved in strains kept under the same conditions. Analysis of different repetitive sequences in their genomes suggested that ribosomal DNA repeats play an important role in the changes in size observed in chromosome XII, whereas SUC genes or Ty elements did not show amplification or transposition processes that could be related to rearrangements of the chromosomes showing these sequences. Karyotype changes also occurred in monosporidic diploid derivatives. We propose that these changes originated mainly from ectopic recombination between repeated sequences interspersed in the genome. None of the rearranged karyotypes provided a selective advantage strong enough to allow the strains to displace the parental strains. The nature and frequency of these changes suggest that they may play an important role in the establishment and maintenance of the genetic diversity observed in S. cerevisiae wild populations.

Blotting, Southern↗
PubMed1998

[Septicemia associated with central venous catheterization in a children's hospital. A multivariate study].

BACKGROUND: The blood stream infections (BSI) are the principal nosocomial infection in the child hospitals. In this study we estimate the incidence of BSI associated with central venous catheterization, and estimate different risk and protective factors, through a multivariate study. MATERIAL AND METHODS: The study have followed in a prospective way during 6 months all the children with central venous catheterization (489 catheters), from the moment of insertion until withdrawal, collecting various data previous to the development of the infection: place of insert, type of catheter, duration, clinic information, microbiology, and the treatments administered through the catheter. In was accomplished an multivariate analysis with logistic regression, for two principal effect variables, the catheter colonization and the catheter related BSI. RESULTS: The incidence of catheter related BSI was 5.5% and for local infection 11.2%. The density of incidence was 3.15 and 6.42 for each 1,000 catheters-day, respectively. The logistic regression model included: colonization of the skin in the insertion point > 15 colonies, days with antibiotics through catheter, use of lipidic parenteral solutions and fever, previous to the infection. The area under the ROC curve was 0.72. CONCLUSIONS: In children with septicemias associated with central catheterization the predictors or sentry criterion for the decision on when to withdraw a catheter are colonization (> 15 colonies) of the insert point, together with the use of lipidic parenteral solutions or extended antibiotic treatment.

Age Factors↗
PubMed1998

Successful treatment of invasive aspergillosis in chronic granulomatous disease by bone marrow transplantation, granulocyte colony-stimulating factor-mobilized granulocytes, and liposomal amphotericin-B.

X-linked chronic granulomatous disease (X-CGD) is a primary immunodeficiency with complete absence or malfunction of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the phagocytic cells. Life-threatening infections especially with aspergillus are common despite optimal antimicrobial therapy. Bone marrow transplantation (BMT) is contraindicated during invasive aspergillosis in any disease setting. We report an 8-year-old patient with CGD who underwent HLA-genoidentical BMT during invasive multifocal aspergillus nidulans infection, nonresponsive to treatment with amphotericin-B and gamma-interferon. During the first 10 days post-BMT, the patient received granulocyte colony-stimulating factor (G-CSF)-mobilized, 25 Gy irradiated granulocytes from healthy volunteers plus G-CSF beginning on day 3 to prolong the viability of the transfused granulocytes. This was confirmed in vitro by apoptosis assays and in vivo by finding nitroblue tetrazolium (NBT)-positive granulocytes in peripheral blood 12 and 36 hours after the transfusions. Clinical and biological signs of infection began to disappear on day 7 post-BMT. Positron emission tomography with F18-fluorodeoxyglucose (FDG-PET) and computed tomography (CT) scans at 3 months post-BMT showed complete disappearance of infectious foci. At 2 years post-BMT, the patient is well with full immune reconstitution and no sign of aspergillus infection. Our results show that HLA-identical BMT may be successful during invasive, noncontrollable aspergillus infection, provided that supportive therapy is optimal.

Amphotericin B↗
PubMed1998

[Lung diseases in HIV-infected children].

Pulmonary diseases, including opportunistic and bacterial infections, lymphoproliferative disorders, and neoplasia, substantially contribute to morbidity and mortality in HIV-infected children. Current treatment modalities are largely successful and thus justify invasive aetiological diagnostic procedures.

AIDS-Related Opportunistic Infections↗