Mandibular fractures in association with chin trauma in pediatric patients

The combination of chin trauma and bleeding from the ear should alert the physician to the possibility of a mandibular fracture. Not all hemotympanums represent basilar skull fractures, especially when they occur in association with chin trauma. Diagnosis of mandibular condylar fractures or temporomandibular joint disruptions can be very difficult. A high index of suspicion and a proper choice of imaging modalities are necessary to ensure a timely diagnosis.

Virus-specific memory T cells are Pgp-1+ and can be selectively activated with phorbol ester and calcium ionophore

Memory lymphocytic choriomeningitis virus (LCMV)-immune cytotoxic T-lymphocyte precursors (CTLp) can be stimulated to proliferate and to mediate specific cytotoxic activity following incubation with phorbol myristate acetate (PMA), calcium ionophore (CaI), and interleukin 2 (IL-2). This protocol can be used to selectively induced virus-specific CTL activity under both bulk culture and limiting dilution conditions, in the absence of added antigen. There is no concurrent stimulation of alloreactive CTLp. Proliferation of the effector Lyt-2+ population in medium containing PMA and CaI requires L3T4+ cells, which can be replaced by adding IL-2, and the development of cytotoxicity is totally IL-2 dependent. The LCMV-specific memory T cells are also characterized by the expression of the Pgp-1 (Ly24) glycoprotein. The availability of this marker, together with the capacity to selectively stimulate primed CTLp in the absence of antigen, should greatly facilitate the analysis of T-cell memory in virus infections.

Phenotypic properties, interleukin 2 production, and developmental origin of a "mature" subpopulation of Lyt-2- L3T4- mouse thymocytes

Two-color flow microfluorometry using monoclonal antibodies to cell surface determinants has shown that a subpopulation of mouse Lyt-2- L3T4- thymocytes, comprising 18% of Lyt-2- L3T4- cells in adult C57BL/6 mice, appears in the thymus late during fetal development. These Lyt-2- L3T4- cells are characterized by lack of expression of determinants recognized by monoclonal antibody J11d, a phenotype characteristic of more "mature" functional T cells. This J11d- subpopulation of Lyt-2- L3T4- thymocytes has now been shown to produce significant quantities of interleukin 2 following mitogen stimulation and to express T-cell receptor molecules recognized by monoclonal antibodies KJ-16 and F23.1. Furthermore, culturing of fetal thymus lobes has shown that precursors of this subpopulation of Lyt-2- L3T4- thymocytes are already present in thymus at 14 days of embryonic development and are thus derived from an intrathymic precursor cell. So, within the mouse thymus, phenotypic changes and acquisition of mature T-cell characteristics occur within a subpopulation of cells originally thought of as exclusively "immature."

Phenotypic analysis of the inflammatory exudate in murine lymphocytic choriomeningitis

The massive inflammation of the cerebrospinal fluid (CSF) which occurs in adult mice injected with lymphocytic choriomeningitis virus (LCMV) has been analyzed by flow microfluorometry (FMF). The great majority of the T cells detected by direct examination of freshly obtained CSF were found to be Lyt-2+, with an almost total absence of L3T4+ lymphocytes. The Lyt-2/L3T4 ratio of lymphocytes in blood was within normal limits. Predominance of the Lyt-2+ subset was confirmed by culturing the CSF cells after mitogenic stimulation. In addition, the T lymphocytes in CSF of cyclophosphamide-suppressed, virus-infected recipients that had been injected 4 d previously with LCMV-immune spleen cells were almost entirely donor Lyt-2+ cells, while the nonlymphoid elements were exclusively of host origin. However this pattern of donor and host T cell distribution was reversed when the LCMV-infected recipients were not immunosuppressed. The frequency of LCMV-specific CTL precursors in CSF taken immediately before the development of symptoms was as low as 1:3,000 cells. Thus most of the T lymphocytes extravasating into the CSF of mice with LCM are passive participants recruited as a consequence of the function of relatively few LCMV-specific effector T cells. The dominance of the Lyt-2+ T cell subset in the CSF of mice with LCM is intriguing.

Expression of Pgp-1 (or Ly24) by subpopulations of mouse thymocytes and activated peripheral T lymphocytes

The expression of Pgp-1 (Ly24) by subpopulations of thymocytes was investigated and a subpopulation of Lyt-2-/L3T4-/J11d- thymocytes was identified which contained significant numbers (80%) of Pgp-1+ cells. Among freshly isolated lymph node T cells but not cortisone-resistant thymocytes, Pgp-1 expression was heterogeneous. Stimulation of T lymphocytes with either concanavalin A or the combination of phorbol myristate acetate plus calcium ionophore resulted in increased Pgp-1 expression which was found to be regulated independently of DNA synthesis and interleukin 2 receptor expression. T cells in the cerebrospinal fluid exudate of mice infected with lymphocytic choriomeningitis virus were also found to be Pgp-1+.

Cefazolin-induced pseudomembranous colitis resulting in perforation of the sigmoid colon

The seventh case of probable cefazolin-induced pseudomembranous colitis is reported. Perforation of the colon necessitated sigmoid resection. The postoperative course was protracted, and illustrates the difficulty of managing advanced pseudomembranous colitis when the oral route of antibiotic administration is not available. Although rare, pseudomembranous colitis related to cefazolin administration is a potentially fatal complication. The routine use of prophylactic antibiotics must be weighed against this possibility.

Acquired lobar emphysema in premature infants with bronchopulmonary dysplasia: an iatrogenic disease?

Five premature infants in whom bronchopulmonary dysplasia developed following prolonged neonatal respiratory support are presented. In all five patients, right middle and/or lower lobe emphysema related to focal obstructing endobronchial masses of granulation tissue subsequently developed. It is speculated that the granulation tissue formed in response to the repeated mechanical trauma of endotracheal tube suctioning.