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Biomedical subjects

J Leitao

Publications and source records attributed to J Leitao.

12 recordsLinked to original sources
PubMed2004

The mef(A) gene predominates among seven macrolide resistance genes identified in gram-negative strains representing 13 genera, isolated from healthy Portuguese children.

Of the 176 randomly selected, commensal, gram-negative bacteria isolated from healthy children with low exposure to antibiotics, 138 (78%) carried one or more of the seven macrolide resistance genes tested in this study. These isolates included 79 (91%) isolates from the oral cavity and 59 (66%) isolates from urine samples. The mef(A) gene, coding for an efflux protein, was found in 73 isolates (41%) and was the most frequently carried gene. The mef(A) gene could be transferred from the donors into a gram-positive E. faecalis recipient and a gram-negative Escherichia coli recipient. The erm(B) gene transferred and was maintained in the E. coli transconjugants but was found in 0 to 100% of the E. faecalis transconjugants tested, while the other five genes could be transferred only into the E. coli recipient. The individual macrolide resistance genes were identified in 3 to 12 new genera. Eight (10%) of the oral isolates and 30 (34%) of the urine isolates for which the MICs were 2 to >500 microg of erythromycin per ml did not hybridize with any of the seven genes and may carry novel macrolide resistance genes.

Bacterial Proteins↗
PubMed2002

Posterior reduction and anterior lumbar interbody fusion in symptomatic low-grade adult isthmic spondylolisthesis: short-term radiological and functional outcome.

The aim of this study was to evaluate the short-term radiological and functional outcome of surgical treatment for symptomatic, low-grade, adult isthmic spondylolisthesis. Twelve patients underwent a monosegmental fusion for symptomatic spondylolisthesis. Posterior reduction with pedicle screw instrumentation was followed by second-stage anterior interbody fusion with a cage. All patients underwent a decompressive laminectomy. At an average of 2.1 (range 1.4-3.0) years following surgery, all patients completed the Oswestry questionnaire, VAS back pain score and a questionnaire detailing their work status. Radiographs were evaluated for maintenance of reduction and fusion. The patients (nine male, three female; mean age 42, range 22-54 years) had experienced preoperative symptoms for an average of 38 (range 6-96) months. An average preoperative slip of 21% (range 11-36%) was reduced to 7% (range 0-17%). Reduction of slip was maintained at latest follow-up, at which time the average VAS score was 2.8 (range 0-8) and the average Oswestry score was 13 (range 0-32). All patients achieved a successful fusion. There were no postoperative nerve root deficits. All patients stated that they would be prepared to undergo the same procedure again if required. Seventy-five percent returned to their pre-symptom work status. Our findings suggest that posterior reduction and anterior fusion for low-grade adult isthmic spondylolisthesis may yield good functional short-term results. A high fusion rate and maintenance of reduction with a low complication rate may be expected. Further follow-up is necessary to evaluate long-term outcome.

Adult↗
PubMed2002

Persistence of oral Candida albicans carriage in healthy Portuguese schoolchildren followed for 3 years.

Little is known about carriage of Candida albicans, the predominant pathogenic yeast in oral infection, in children. We cultured buccal mucosal and gingival swabs from 150 Portuguese children to investigate the prevalence of C. albicans at baseline (before dental treatment), post-treatment, and 12, 24, and 36 months post-baseline. The children, aged 8 to 11 years at baseline, had no systemic disease or clinical symptoms of oral candidiasis. At each successive visit, respectively, 47, 32, 21, 27, and 28% of children were C. albicans positive, resulting in an almost 50% reduction in prevalence from baseline to post-treatment (P < 0.0005). Children who carried C. albicans at one visit had 3 to 20 times greater odds of carrying C. albicans at another visit. C. albicans was cultured from 12 children at all time-points and from 10 children at four time-points. Children with oral C. albicans frequently maintained carriage over time, even with regular dental care.

Age Factors↗
PubMed1999

Pyogenic spondylitis.

Twenty-nine patients with pyogenic vertebral osteomyelitis were reviewed retrospectively after an average follow-up of 3.7 years. We identified 17 patients with predisposing factors (10 diabetes, 4 urinary tract infection, 2 HIV-positive, 1 rheumatoid arthritis). No patient presented with a febrile illness. The lumbar spine was involved in 15 patients. Eighteen patients had neurological impairment at presentation. Eleven patients who were neurologically intact had needle biopsies and the remaining 18 patients who were neurologically compromised had an open decompression. Staphylococcus aureus was cultured in 14 patients. Although spinal tuberculosis is relatively common in our environment it is important to obtain a tissue diagnosis in order to exclude pyogenic vertebral osteitis.

Adult↗
PubMed1995

Outbreak of Shigella sonnei infection traced to imported iceberg lettuce.

In the period from May through June 1994, an increase in the number of domestic cases of Shigella sonnei infection was detected in several European countries, including Norway, Sweden, and the United Kingdom. In all three countries epidemiological evidence incriminated imported iceberg lettuce of Spanish origin as the vehicle of transmission. The outbreaks shared a number of common features: a predominance of adults among the case patients, the presence of double infections with other enteropathogens, and the finding of two dominant phage types among the bacterial isolates. In Norway 110 culture-confirmed cases of infection were recorded; more than two-thirds (73%) were adults aged 30 to 60 years. A nationwide case-control study comprising 47 case patients and 155 matched control individuals showed that the consumption of imported iceberg lettuce was independently associated with an increased risk of shigellosis. Epidemiological investigation of a local outbreak incriminated iceberg lettuce from Spain, consumed from a salad bar, as the source. The presence of shigellae in the suspected food source could not be documented retrospectively. However, high numbers of fecal coliforms were detected in iceberg lettuce from patients' homes. Three lettuce specimens yielded salmonellae. The imported iceberg lettuce harbored Escherichia coli strains showing resistance to several antimicrobial agents, including ampicillin, ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole. During the outbreak it is likely that thousands of Norwegians and an unknown number of consumers in other countries were exposed to coliforms containing antibiotic resistance genes.

Adolescent↗
PubMed1989

Production of aflatoxin B1 by Aspergillus ruber THOM and CHURCH.

Production of aflatoxins by Aspergillus ruber THOM and CHURCH was first reported by KULIK and HOLADAY (1967), although these results have lacked confirmation. In this paper we provide evidence that this fungal strain produces aflatoxins. This finding has implications for food hygiene, especially in countries where such moulds are used in the preparation of foodstuffs.

Aflatoxin B1↗
PubMed1987

The induction of DNA strand breaks at specific sites by N-nitroso-N-ethylurea depends on the phases of the cell cycle.

Synchronized root meristems of Pisum sativum were treated at each phase of the cell cycle with 6.25 mM N-nitroso-N-ethylurea. DNA extracted from treated cells and run in agarose gel electrophoresis exhibits a series of discrete fragments with length below 2500 bp and a significant number of unspecific single-stranded breaks (or alkali-labile sites). Experiments with micrococcal nuclease indicated that the nucleosomal organization of the chromatin is not responsible for the generation of the discrete fragments: it seems that their appearance is associated with a preferable attack of the mutagen at specific sites, characteristic for the plant genome. Moreover, a cell cycle dependent release of the discrete fragments was found with maximum at G1-S and minimum at mitosis. The model experiments designed to clarify this observation suggest that it might be determined from the cell cycle dependent fluctuation in the accessibility of the chromatin DNA and/or the process of excision-repair.

Biological Transport↗
PubMed1987

Action of phosphine on production of aflatoxins by various Aspergillus strains isolated from foodstuffs.

Phosphine is a food fumigant, used until now as an insecticide and rodenticide. The present work researches the action of phosphine treatment on growth and aflatoxin production of 23 Aspergillus strains. Production of aflatoxins B1, B2, G1, and G2 decreased in almost all cases by a ratio of 10 to 100. Phosphine treatment therefore seems favorable to prevent growth of various Aspergillus strains, in the context of keeping food safe.

Aflatoxins↗
PubMed1975

Gastroscopy with directed biopsy and routine x-ray examination in the diagnosis of malignancies of the stomach. A retrospective study.

The examinations were performed in 418 patients with malignancy or an ulcer of the stomach. In all cases the Cancer Registry of Norway was asked for the final diagnosis and date of death. The diagnosis of malignancy was based on histology on operated or autopsy specimens, and the surviving cases were re-examined by answering a questionnaire. At the time of the primary examination a total of 103 cases of malignancies were found, of whom 41 were women. 84 patients had not been operated on previously. Among these 7 cases of early carcinoma were found. In 19 patients a partial gastrectomy had been performed. A false diagnosis of benign lesion was given on biopsy in 2 per cent, by gastroscopy in 8, and by X-ray examination in 31 per cent. A definite diagnosis of malignancy was made correctly by the same procedures in 95, 53 and 16 per cent, respectively. After 30 months of observation 16 cases of malignant lesions were reported among the patients (315) who had an ulcer of the stomach with benign histology on directed biopsy at the primary examination. A false benign diagnosis had been made in 33 per cent of 119 with malignancy by X-ray examination, in 10 per cent by gastroscopy, and in 15 per cent by histology on biopsy. The corresponding percentages in the total material of cases with benign and malignant lesions were 10.2, 2.9, and 4.3, respectively. In cases with previous partial gastrectomy, and in those with early cancers much higher rates of false negative diagnosis of malignancy has so far been suggested in 12 per cent of cases with benign ulcers, a gastroscopical diagnosis has been suggested in 22 per cent, and a bioptical in none. A combination of diagnostic procedures provided a correct diagnosis of malignancy in 118 out of 119 patients.

Adolescent↗
PubMedDate not supplied

Preventive measures for microflora and mycotoxin production in foodstuffs.

The conservation of foodstuffs by chemical or physical methods is now practiced on a wide scale. Certain procedures (drying, use of pesticides) are well proved and are used on an industrial scale, although in certain situations they are not without risk to human health. New techniques (controlled atmospheres, irradiation, fumigation) are in use and will undoubtedly see further development for conservation of seeds and cereals in both industrialized and non-industrialized countries. In the latter case, the use of cost-effective fumigants may be of particular value. Preventive measures for the control of molds in foodstuffs are discussed in this report.

Food Contamination↗