Defective calcium binding to fibrillin-1: consequence of an N2144S change for fibrillin-1 structure and function.

Fibrillin-1 is a major structural component of 10-12 nm connective tissue microfibrils and has a modular organisation that includes 43 calcium binding epidermal growth factor-like (cbEGF) domains and seven transforming growth factor beta-binding protein-like (TB) domains. Mutations in the fibrillin-1 (FBN1) gene cause the Marfan syndrome (MFS) and related connective tissue disorders. We have previously investigated an N2144S change, identified in a MFS patient, which removes one of the key calcium binding ligands within cbEGF domain 32. In this study the structural consequences of the N2144S amino acid change for the folding and calcium binding properties of mutant and wild-type TB6-cbEGF32 and cbEGF32-33 domain pairs have been analysed by nuclear magnetic resonance. The presence of an N2144S substitution does not alter the native fold of either the TB6 domain, or cbEGF domains 32 and 33. Comparison of calcium dissociation constants measured for the wild-type and mutant pairs shows that: (i) the affinity of cbEGF32 is weakly enhanced by N-terminal linkage of TB6 relative to cbEGF32 in isolation; (ii) the affinity of cbEGF32 is approximately ninefold decreased by the N2144S substitution in the TB-cbEGF pair; and (iii) reduced affinity of cbEGF32 does not result in lower affinity of cbEGF33 for calcium. Together, these data suggest that the TB6-cbEGF32 linkage is flexible and the structural effect of the mutation is localised to the interdomain linkage. We have also investigated the effect of defective calcium binding to cbEGF32 on fibrillin-1 produced by N2144S MFS fibroblasts. 35S-pulse-chase analysis shows that the N2144S substitution does not detectably affect fibrillin-1 biosynthesis, rate of secretion or processing. Deposition of reducible fibrillin-1 into the extracellular matrix was also unaffected. The implications of these results for the assembly and properties of the microfibril are discussed.

Bacteremia in children: an outpatient clinical review.

In a 20-month period, 1,783 children seen in the pediatric outpatient department had blood cultures performed and 117 (6.5%) of these children had bacteremia. Two thirds of the isolates were Diplococcus pneumoniae and Hemophilus influenzae b. Ninety-three percent of children with H. influenzae b bacteremia and 20% of children with pneumococcal bacteremia had soft tissue involvement at the initial visit. Most children with positive blood cultures (102) were previously well and beyond the newborn period and many (46) had seemingly trivial illnesses initially: upper respiratory tract infection, fever of unknown origin, otitis media, and diarrhea. In the absence of soft tissue infection, the latter three diagnoses correlated best with bloodstream invasion. Nineteen children had persistent bacteremia and five developed soft tissue complications not noted initially. Two factors, age between 7 and 24 months and temperature between 39.4 and 40.6 C, showed increased specificity for bacteremia but were sensitive only for pneumococcal disease. A temperature larger than or equal to 40.5 C showed more specificity for bacteremia than lesser fevers. A white blood cell count greater than 20,000/cu mm was poorly sensitive, and pulmonary infiltrates were neither specific nor sensitive for positive blood cultures. Five bacteremic children had aseptic lymphocytosis in the cerebrospinal fluid. Two days of intravenous antibiotic therapy and eight days of oral therapy were adequate for pneumococcal bacteremia without soft tissue involvement. This therapy may not be without soft tissue involvement. This therapy may not be ideal, however, since other routes and duration of therapy were not evaluated.

Idiopathic external coronal resorption. Case report.

External resorption occasionally affects the coronal tissues of unerupted teeth. In young patients these teeth may be interpreted radiographically as being carious. The resorption frequently does not extend to the pulp chamber. Loss of integrity of the reduced enamel epithelium may predispose to these changes. This paper reports the features of an example of idiopathic external coronal resorption.

Irradiation as the primary management of stage I and II adenocarcinoma of the breast: analysis of the RTOG breast registry.

The radiation therapy oncology group, a 36-member national study group, has collected, by means of a registry, 234 patients treated with primary irradiation for UICC Stage I and II adenocarcinoma of the breast. Analysis of these patients has revealed a 5-year actuarial survival rate of 83% for Stage I and 68% for Stage II. The local-regional failure rate for all 234 patients was 8.5% (20/234), and 16.6% (17/102) for those patients followed for a minimum of 3 years. The local failure rate for T1 tumors was negligible, being 1.7% (2/117), regardless of whether or not complete excision of tumor was performed prior to irradiation. For T2 tumors, the local failure rate was 9.7% (9/93) if there was preirradiation tumor excision, but increased to 29.2% (7/24) if the preirradiation surgery was limited to incisional or needle biopsy only. There were six severe complications (2.6%), and all of these were cases of breast fibrosis. There were 14 other complications but these were judged to be of only mild to moderate severity. Eighty-four percent of the patients had an acceptable cosmetic result with either no difference or only a mild to moderate difference between the treated and untreated breast.

An histological study of cystic lesions following pulp therapy in deciduous molars.

The clinical and radiographic features of a group of apical periodontal cysts associated with endodontically treated deciduous molar teeth have been previously reported. The histological description and histochemical investigation of distinctive intraepithelial inclusions are described in this paper. The chronic inflammatory response is dominated by plasma cells and the wall contains an amorphous, eosinophilic material that is shown to contain phenolic groupings similar to those present in the intracanal medicaments used clinically. A direct relationship is proposed between the inclusions, continued antigenic stimulation within the lesions and their clinical behaviour.

Six families prone to ovarian cancer.

Six families are presented with multiple cases of ovarian cancer, mainly serous cystadenocarcinoma. Three families had concomitant aggregation of breast cancer, suggesting genetic determinants common to both tumors. The exceptional cancer risk in these families prompted prophylactic oophorectomy in 14 asymptomatic women from four families. Review of the original microscopic sections from 8 women revealed that 3, representing two families, had abnormalities of ovarian surface epithelium and mesothelial tissue, which may be of etiologic significance and portend neoplastic changes. To enable early detection and prevention of ovarian cancer, new diagnostic techniques and etiologic studies should be applied whenever possible to high-risk families.