Plasma cell cheilitis.

Plasma cell cheilitis is a rare, idiopathic mucosal condition, which has previously been given scant attention among oral and maxillofacial publications. We present a case of plasma cell cheilitis, with the differential diagnosis and options for treatment.

A complication of tongue piercing.

The trend of tongue piercing is becoming more popular. A patient with Ludwig's angina, secondary to recent tongue piercing, is presented. The management of the patients and the implications of tongue piercing are discussed.

The aetiology of maxillofacial injuries and the seat belt law.

Between the period 1 February 1981 and 31 January 1985, 678 patients with maxillofacial injuries were referred to the Department of Oral and Maxillofacial Surgery, at Southampton General Hospital. The commonest two aetiological factors in this group of patients were alleged assaults and road traffic accidents. Seat belt legislation in the United Kingdom was introduced on 1 February 1983. The compliance with seat belt usage rose to 90-95% for all front seat occupants after the legislation. The incidence of maxillofacial trauma cases arising in the front seat occupant group of patients dropped from 20.9% (78 patients) in the 2 years before the legislation to 5.9% (18 patients) in the 2 years after the legislation. The difference is statistically significant (p less than 0.001).

Umbilical cord stricture associated with intrauterine fetal demise. A report of two cases.

Two cases occurred of umbilical cord stricture with intrauterine fetal demise. The cause of this defect is unknown. Our cases represented the common findings of stricture at the squamoamnionic junction and an increased incidence with twin gestations. One fetus had a reactive nonstress test at 30 1/2 weeks and died two days later.

Ongoing block of Schwann cell differentiation and deployment in dystrophic mouse spinal roots.

In the spinal roots of dystrophic mice, there are bundles of unensheathed axons and two populations of axon-associated cells: the typical Schwann cells of myelinated fibers and 'uncommitted' cells at the margin of the bundles. Because these 'uncommitted' cells continue to divide in adult animals but fail to ensheath the axons they appose, they can be labelled with tritiated thymidine. In the present experiments, we show that these cells may differentiate into typical Schwann cells of myelinated or unmyelinated fibers when spinal roots from [3H]thymidine-labelled dystrophic mice are grafted into the sciatic nerves of non-dystrophic animals. Thus, this study demonstrates that the 'uncommitted' cells of dystrophic spinal roots are undifferentiated Schwann cells whose differentiation in the intact spinal roots is continuously prevented by some unknown mechanism.

Schwann cell multiplication in Trembler mice.

Peripheral nerves of the mutant mouse Trembler are characterized by a severe myelin deficit and an increased number of Schwann cells. On the basis of radioautographic and quantitative morphologic investigations, the present study documents: i an abnormal persistence of post-natal Schwann cell proliferation in Trembler mouse nerves which, in unaffected animals, are composed of myelinated fibres; ii normal morphology, numbers and proliferation of Schwann cells in the unmyelinated (Remak) fibres of Trembler mice; and iii replication of the increased rate of Schwann cell multiplication as well as the myelin deficit, when segments of Trembler sciatic nerves are transplanted into the sciatic nerves of normal mice. Thus, the continued proliferation of Trembler Schwann cells must be related to the primary inability of these cells to produce and maintain a normal myelin sheath; axonal or general systemic abnormalities do not appear to play a major role in the pathogenesis of these disorders in the Trembler mouse.

Persistent multiplication of axon-associated cells in the spinal roots of dystrophic mice.

Axons which lack Schwann cells characterize the spinal roots of dystrophic mice. In these nerves, two types of cells are associated with large axons-typical Schwann cells which ensheath and myelinate individual axons and "uncommitted" cells which closely contact some axons but do not unsheath them normally. Although neonatal Schwann cell multiplication in dystrophic spinal roots is less than normal, the "uncommitted" cells continue to multiply in adult animals. Thus, these cells are presumably responsive to the mitogenic stimulus of axons, but are unable to extend radially and longitudinally to form a myelin sheath. This disorder of axon-sheath cell interactions could be due to an intrinsic abnormality of Schwann cells or a failure of the mechanisms whereby axons induce Schwann cell differentiation.