Comparative study of five different DNA fingerprint techniques for molecular typing of Streptococcus pneumoniae strains.

The aim of this study was to identify the strengths and weaknesses of five DNA fingerprint methods for epidemiological typing of Streptococcus pneumoniae. We investigated the usefulness of (i) ribotyping, (ii) BOX fingerprinting with the BOX repetitive sequence of S. pneumoniae as a DNA probe, (iii) PCR fingerprinting with a primer homologous to the enterobacterial repetitive intergenic consensus sequence, (iv) pulsed-field gel electrophoresis of large DNA fragments, and (v) restriction fragment end labeling to detect restriction fragment length polymorphism of small DNA fragments. Twenty-eight S. pneumoniae strains isolated from the blood and/or cerebrospinal fluid of 21 patients were analyzed. Genetic clustering among the 28 strains was independent of the DNA fingerprint technique used. However, the discriminatory power and the similarity values differed significantly among the individual techniques. BOX fingerprinting, pulsed-field gel electrophoresis, and restriction fragment end labeling provided the highest degree of discriminatory power. Furthermore, the ease with which computerized fingerprint analysis could be conducted also varied significantly among the techniques. Ribotyping, BOX fingerprinting, and restriction fragment end labeling were very suitable techniques for accurate computerized data analysis. Because of their high discriminatory potential and ease of accurate analysis, we conclude that BOX fingerprinting and restriction fragment end labeling are the most suitable techniques to type pneumococcal strains.     

Genomic DNA fingerprinting by restriction fragment end labeling.

A typing method for bacteria was developed and applied to several species, including Escherichia coli and Actinobacillus actinomycetemcomitans. Total genomic DNA was digested with a restriction endonuclease, and fragments were enabled with [alpha-32P]dATP by using the Klenow fragment of DNA polymerase and separated by electrophoresis in 6% polyacrylamide/8 M urea (sequencing gel). Depending on the restriction endonuclease and the bacterium, the method produced approximately 30-50 well-separated fragments in the size range of 100-400 nucleotides. For A. actinomycetemcomitans, all strains had bands in common. Nevertheless, many polymorphisms could be observed, and the 31 strains tested could be classified into 29 distinct types. Furthermore, serotype-specific fragments could be assigned for the three serotypes investigated. The method described is very sensitive, allowing more distinct types to be distinguished than other commonly used typing methods. When the method was applied to 10 other clinically relevant bacterial species, both species-specific bands and strain-specific bands were found. Isolates from different locations of one patient showed indistinguishable patterns. Computer-assisted analysis of the DNA fingerprints allowed the determination of similarity coefficients. It is concluded that genomic fingerprinting by restriction fragment end labeling (RFEL) is a powerful and generally applicable technique to type bacterial species.     

The significance of an isolated central nervous system relapse, occurring as first relapse in children with acute lymphoblastic leukemia

In a retrospective study, which comprised the whole Dutch childhood population of approximately 3 million children, the authors assessed the influence of an isolated meningeal relapse, occurring as first relapse, together with some patient and treatment characteristics on prognosis in 142 children with acute lymphoblastic leukemia (ALL). Until their first relapse, patients were initially treated according to standard protocols, whereas the treatment for relapse was heterogeneous. Concerning the probability of achieving a second complete remission (CR) it appears that the duration of the first CR is the single most important prognostic factor. The duration of the first CR is also the most important factor with regard to the duration of the second CR, upon which also age and sex have a significant influence. Concerning the survival from the time of central nervous system (CNS) relapse, again the duration of the first CR appears to be the most important prognostic factor, followed by age and the institution of systemic reinduction treatment. Other factors, such as initial leukocyte count, attainment of first CR within 48 days, type of reinduction treatment, and the cerebral spinal fluid (CSF) blast count at the time of relapse, have a less important, but nevertheless significant influence on survival. The median survival from the time of CNS relapse is 25 months, the 5-year survival is 25%, whereas the ultimate survival will be less than 20%. From 90 patients who developed second or subsequent relapses, 75% experienced a bone marrow relapse during the follow-up period. From this study the authors conclude that CNS relapse in children with ALL carries a grave prognosis, which requires the institution of intensive retreatment programs.     

Eosinophilic granuloma of the head and neck: CT and MRI features in three cases

We report the radiological findings and more specifically the MRI features in three typical cases of Langerhans' cell histiocytosis of the head and neck. All three cases were of solitary eosinophilic granuloma of bone: two mandibular and one temporal bone lesion. Reports on the MRI features of head and neck eosinophilic granulomas are rare.     

Lack of association between cytomegalovirus infection, HLA matching and the vanishing bile duct syndrome after liver transplantation.

In this study we evaluated the association between cytomegalovirus infection alone or in relation to human leukocyte antigen matching and the development of vanishing bile duct syndrome, a form of chronic hepatic allograft rejection. A total of 81 consecutive liver transplant recipients were studied. Cytomegalovirus infection developed in 46 recipients (57%), and vanishing bile duct syndrome occurred in 9 recipients (11%). Cytomegalovirus infection developed in only five of the nine patients with vanishing bile duct syndrome. Univariate analysis of pretransplant recipient/donor cytomegalovirus serological tests and human leukocyte antigen typing showed they were not significant risk factors for the development of vanishing bile duct syndrome. Time-dependent analysis of cytomegalovirus infection after transplantation as a risk factor for vanishing bile duct syndrome, in a multivariate analysis with human leukocyte antigen match, showed no statistical significance. In our study, no association was found between cytomegalovirus infection alone or in relation to class I or II human leukocyte antigen match and the subsequent development of vanishing bile duct syndrome.     

Magnetic resonance relaxation times of normal tissue in the course of chemotherapy: a study in patients with bone sarcoma

To study the effect of chemotherapy on normal fat, skeletal muscle, and bone marrow, T1 and T2 relaxation times were measured in 15 patients with bone sarcoma before and after each cycle of preoperative chemotherapy. A section plane containing the tumor and if possible the nonaffected extremity was imaged with combined multiecho spin echo and inversion recovery pulse sequences. T1 and T2 relaxation times were calculated in the normal-appearing tissues. Although some variation was found in the values in the individual patient and between patients, no systematic changes of relaxation times of fat, muscle, or bone marrow occurred in the course of treatment. We conclude that the chemotherapy used in bone sarcoma has no effect on relaxation times of normal fat, muscle, and bone marrow, and that therefore these tissues may serve as a reference for the signal intensity of tumor.     

Glottic and supraglottic carcinoma: a retrospective comparison of radiotherapy alone with sandwich therapy in 366 patients

From 1971 through 1982, 442 patients with laryngeal carcinoma were seen at the Leiden University Hospital. They were treated either with radiotherapy alone, sandwich therapy (pre- and postoperative radiotherapy) or by surgery followed by postoperative irradiation. Three hundred and sixty-six patients with glottic or supraglottic tumours could be analysed with respect to two different treatments, complications of treatment and some prognostic factors. Two endpoints of analysis were used: disease-free interval and survival to cancer death. In patients with glottic or supraglottic carcinoma, the survival of patients with advanced disease, treated with radiotherapy only, was worse as compared to the survival of the same category of patients who were treated with sandwich therapy (p less than 0.005). In patients with small glottic tumours, radiotherapy alone was mostly used. In small supraglottic tumours, the survival with both therapy policies was equal. Persistent hoarseness in patients with small glottic tumours, treated with radiotherapy only, is of predictive value for the development of a recurrence (p less than 0.001). There was no influence on prognosis of histological differentiation of the tumour. It appeared that interruption of radiotherapy for more than two days had an adverse effect on survival in patients with glottic carcinoma (p = 0.0001). Finally, the occurrence of second malignancies was analysed. It was found that 19% had a second malignancy. Almost 60% of them were lung cancers.     

The value of aspiration cytologic examination of the breast. A statistical review of the medical literature.

The decision to perform surgery in patients with a breast mass usually is made on the basis of combined diagnostic information, with fine-needle aspiration cytologic examination (FNAC) playing a central role. To determine and compare the quality of FNAC of the breast, a search was performed of the English literature for articles with quantitative information about their results. Twenty-nine such articles, containing 31,340 aspirations, were identified and summarized. Required data were extracted from these articles. These numbers were analyzed with the use of a two-by-four contingency table to relate the FNAC result (definitely malignant, suspect, benign, or unsatisfactory cytologic material) with the final diagnosis (malignant or benign breast disease). Test characteristics such as sensitivity, specificity, and the likelihood ratios for the four different FNAC results were derived for each study and compared. There was a striking difference between studies with regard to the probability of a particular FNAC upshot (e.g., in patients with breast cancer, the chance of obtaining definitely malignant cytologic material ranged from 0.35 to 0.92), the sensitivity (range, 0.65 to 0.98), the specificity (range, 0.34 to 1.0), and likelihood ratios. In the opinion of the authors, it is virtually impossible to infer general test characteristics of FNAC of the breast from the medical literature because of differences in methods and different biases. At best, the maximum attainable performance of this test can be described. For the development of a policy for breast mass management, the local test characteristics of this highly operator-dependent test should be established.