Advances in understanding cell interactions in tissue resorption. Relevance to the pathogenesis of periodontal diseases and a new hypothesis

Much of the connective tissue degradation that takes place in periodontal diseases is mediated by proteolytic enzymes. Previous studies have focused on the action of proteinases released by invading polymorphonuclear neutrophils and macrophages, and bacterial enzymes. In view of recent work establishing that resident connective tissue cells can be induced by cytokines to bring about the destruction of their own matrix, we propose a new hypothesis. In this we envisage that a critical step is the interaction of bacterial antigens with inflammatory cells, resulting in the production of a cytokine, interleukin-1. Our interpretation of in vitro evidence is that the loss of connective tissue attachment and bone matrix resorption in periodontal diseases is mediated by metalloproteinases such as collagenase and stromelysin released by cells of the periodontium. Such proteolytic destruction can be induced by interleukin-1, whose production may not be dependent on a specific microbial flora but may be triggered by a number of organisms. It is now clear that interleukin-1 has multiple actions on both immune and non-immune cells; these include the induction of lymphocyte differentiation and proliferation and the stimulation of bone and cartilage resorption, and prostaglandin and metalloproteinase synthesis by connective tissues. It seems likely that further knowledge about the production and function of this cytokine will have an increasing impact in many diseases that involve resorption, particularly since interleukin-1-like molecules can be produced by cell types other than monocytes/macrophages, including keratinocytes and fibroblasts.     

Rhizomelic chondrodysplasia punctata: 16-year follow-up of a child from birth

A boy with rhizomelic chondrodysplasia punctata, diagnosed on the laboratory evidence of a high plasma concentration of phytanic acid and a low erythrocyte concentration of plasmalogens, has been followed from birth to the age of 16 years. The clinical pattern (somatic, skeletal and neurological) tallies with published findings in this disease. Unusual findings are the associated epilepsy, confirmed by EEG, and the long survival. CT brain scan and MRI showed cortical and subcortical atrophy but not gyral abnormalities or demyelination.

---

Sommario Viene descritto il caso di un bambino affetto da condrodisplasia punctata rizomelica seguito dalla nascita fino ai 16 anni. La diagnosi clinica, efettuata in base alle caratteristiche somatiche, scheletriche e neurologiche del paziente è stata confermata dai reperti di laboratorio (alta concentrazione plasmatica di acido fitanico, bassa concentrazione di plasmalogeni eritrocitari). Come correlati inusuali del quadro clinico vanno segnalati l'associazione con epilessia e a la lunga sopravvivenza. La TAC e la RNM cerebrale hannovaltresì documentato atrofia corticale e sottocorticale ma non anomalie della girazione o demielinizzazione.

     

Errors in the measurements of T2 using multiple-echo MRI techniques. II. Effects of static field inhomogeneity

The accurate estimation of the spin-spin relaxation time T2 is an important goal in magnetic resonance imaging particularly because it can be used for quantitative tissue characterization. The spin-spin relaxation time T2 may be estimated using multiecho pulse sequences, but the accuracy of the estimate is dependent on the fidelity of the spin-echo amplitudes, which may be severely compromised by rf pulse and static field imperfections. In this paper, the effects of static field inhomogeneities are investigated. The propagation of the errors introduced by off-resonance effects are analyzed through computer simulations and analytical solutions of the Bloch equations. A series of experiments performed on a simple tissue phantom using a whole-body imaging system operating at 6.35 MHz corroborates the simulation and analytical results. For accurate measurements of T2 using a whole-body imaging system it is necessary to correct for these inhomogeneities. A correction scheme which would enable a more accurate estimate of T2 is currently under investigation.     

The value of ultrasound in the diagnosis of renal failure

Seventy-four patients with impaired renal function were investigated by ultrasound. By assessing renal length, renal echogenicity and collecting system dilatation, one can establish whether renal function is impaired by chronic or acute renal changes or by obstructive changes.     

Comparative study of 3 therapeutic methods for Pouteau Colles' fracture. Apropos of 97 cases

Results of three therapeutic modalities used for the treatment of a homogeneous series of patients with a Pouteau Colles fracture are analyzed. Orthopedic treatment provided deceiving results. Pinning was, on the contrary, very effective, intrafocal pinning with immediate mobilization of the wrist appearing perfectly effective. Few complications were reported in contrast to plastered immobilizations. Good results were obtained in 80% of cases and functional recovery was rapid, indicating that this method represents undoubted progress when compared with conventional therapies.     

Caustic injuries to the esophagus in children

The ingestion of caustic chemical agents, usually accidentally by children, produces a wide range of injuries from minor mouth burns to necrosis of the esophagus and stomach. The type of agent, amount, concentration, and duration of exposure are the determining factors. The treatment for the average burn is fairly well standardized, but the serious injuries require prompt recognition of complications and appropriate therapy to prevent more serious complications.