K3-mediated evasion of CD8(+) T cells aids amplification of a latent gamma-herpesvirus.

The murine gamma-herpesvirus-68 (MHV-68) K3 protein, like that of the Kaposi's sarcoma associated herpesvirus, down-regulates major histocompatibility complex (MHC) class I expression. However, how this contributes to viral replication in vivo is unclear. After intranasal MHV-68 infection, K3 was transcribed both during acute lytic infection in the lung and during latency establishment in lymphoid tissue. K3-deficient viruses were not cleared more rapidly from the lung, but the number of latently infected spleen cells was reduced and the frequency of virus-specific CD8(+) cytotoxic T lymphocytes (CTLs) was increased. CTL depletion reversed the viral latency deficit. Thus, a major function of K3 appears to be CTL evasion during viral latency expansion.

Antisense suppression of p107 inhibits 3T3-L1 adipocyte differentiation.

The murine 3T3-L1 preadipocyte cell line is well characterized for its capacity to undergo differentiation into adipocytes under appropriate hormonal stimulation. p107, a member of the retinoblastoma tumor suppressor gene family has been shown to be dramatically upregulated during the early requisite clonal expansion phase of 3T3-L1 adipogenesis; however, a functional consequence has yet to be described. A phosphorothioate antisense RNA approach was utilized to determine if inhibition of p107 expression would block or perturb adipocyte differentiation. A series of three phosphorothioate oligonucleotides in antisense orientation was generated, designated AS1, AS2, and AS3 along with a sense control oligonucleotide complementary to AS1 and added to postconfluent cells at a concentration of 20 and 50 microM throughout hormonally stimulated differentiation. Treatment of cells with either concentration of the sense, AS1, AS2, or 20 microM AS3 oligonucleotides had little effect on either Oil Red O lipid accumulation or induction of p107 protein levels. In contrast, treatment with 50 microM AS3 inhibited the increase in p107 protein levels and led to a complete block in differentiation as detected by Oil Red O lipid accumulation and inhibition of adipocyte-specific mRNA expression. In addition, treatment with AS3 led to a significant inhibition of cellular proliferation associated with clonal expansion. Combined, these results provide strong evidence supporting a functional role for p107 in 3T3-L1 adipocyte differentiation.

Spontaneous cerebrospinal fluid otorrhea from defects of the temporal bone: a rare entity?

Cerebrospinal fluid (CSF) otorrhea is usually associated with a history of trauma or previous surgery. Spontaneous CSF otorrhea is uncommon. When such spontaneous CSF leakage occurs, it may be associated with dural herniation, with the production of conductive hearing loss from impingement on the ossicles. This type of leakage has characteristic findings which, if recognized, can lead to earlier diagnosis and avoidance of complications. A review of the world literature revealed 44 reported cases. This report presents the authors' experience with 12 patients with spontaneous CSF leakage from temporal bone defects. This entity may be more prevalent than is reported. The differential diagnosis and management of CSF otorrhea (secondary to temporal bone defects) are discussed and representative cases are presented.

Aberrant internal carotid artery.

An aberrant internal carotid artery (ICA) in the middle ear is rare. If unrecognized, it may lead to massive hemorrhage or other catastrophic results during even a minor surgical procedure of the tympanic membrane or middle ear. Recognition of this entity is particularly significant to the primary care or emergency department physician who performs tympanocentesis as a routine part of clinical practice. We present the management and radiographic findings of a case of aberrant ICA referred because of persistent bleeding following a minor surgical procedure. The possibility of an anomalous artery in the middle ear had been recognized during surgery. The procedure was aborted and the patient referred for definitive care.

Leiomyosarcoma of the skull base-a diagnostic challenge.

Soft tissue sarcomas often present a frustrating diagnostic challenge for the pathologist as well as the surgeon. Despite the development of better defined criteria for histopathologic and immunohistochemical evaluation, definitive diagnosis may not be immediately apparent. We report two cases of leiomyosarcoma of the skull base that presented with the clinical diagnosis of schwannoma, a diagnosis confirmed on initial histopathologic examination. It was only after closer review and special immunohistochemical studies that the diagnosis of leiomyosarcoma was made. The methods for diagnosing such tumors using both standard histopathologic criteria and immunohistochemical methods are reviewed. We suggest that all extracranial soft tissue tumors of the skull base be examined by both techniques to avoid delayed or missed diagnosis.

Temporal bone: three-dimensional CT. Part I. Normal anatomy, techniques, and limitations.

Three-dimensional (3D) surface renderings of the temporal bone were created from routine axial computed tomographic (CT) images in 15 subjects and in cadaver specimens. The displayed anatomy was correlated with these specimens, as well as with images from the routine study. Six sets of viewing angles were derived for optimal display of surgically important surface landmarks, such as the suprameatal triangle and supramastoid crest. The 3D CT images were found to be of excellent quality and permitted a global view of the temporal bone surface anatomy. Bone depletion artifacts ("pseudoforamina") posed a potentially serious problem in evaluating the tegmen and wall of the sigmoid sulcus, being present in eight of 20 cases. Three-dimensional CT may be a useful adjunct to routine temporal bone imaging.

Temporal bone: three-dimensional CT. Part II. Pathologic alterations.

Three-dimensional (3D) surface renderings were obtained from routine axial computed tomographic (CT) images in 15 patients with a variety of complex temporal bone abnormalities. The 3D CT reformations served as an adjunct to conventional sectional CT examination. While no diagnosis was substantially changed because of the 3D CT images, they did provide a more global perspective in cases of large tumors and fractures and at the postmastoidectomy site. Three-dimensional CT surface reformations are now practical and may be potentially useful for visualizing temporal bone lesions characterized by complex destructive change.

Expression and function of HLA-A2.1 in transgenic mice.

We have derived a number of transgenic mouse lines which express the human major histocompatibility complex class I gene HLA-A2.1. Two lines carry the complete human HLA-A2.1, the others bear a recombinant gene in which the HLA-A2.1 coding regions are fused to the H-2Kb promoter. Analysis of transgenic spleen cells by immunofluorescence demonstrates that these mouse cells express HLA-A2.1 on their surface in association with mouse beta 2-microglobulin (beta 2m), confirming that HLA-A2 does not require human beta 2m to be expressed at the cell surface. The cells contain more HLA mRNA than endogenous H-2 class I mRNA. There is also a large pool of non-beta 2m-associated HLA heavy chain inside the cell. In contrast the amount of HLA:beta 2m complex is low. Thus, in transgenic mice HLA-A2 seems to compete poorly with H-2 heavy chains for mouse beta 2m. The HLA-A2.1 transgenic mice do not produce influenza-virus-specific cytotoxic T cells (CTL) restricted to the HLA transgene, at least in sufficient numbers to be measured in a direct bulk CTL assay. The dominance of H-2-restricted clones may be the result of quantitative rather than qualitative factors. However, HLA-A2.1 transgenic spleen cells are effective in stimulating an allogeneic CTL response in normal mice. This response is not H-2 restricted. Cold target inhibition studies show that there are at least two populations of CTL, one of which is specific for HLA-A2.1 on mouse cells. This result suggests that at least some allo-CTL are directed against major histocompatibility complex plus "self-peptide".

Frey's syndrome: treatment with topical glycopyrrolate.

Gustatory sweating and flushing of the facial skin, or Frey's syndrome, is fairly common after parotidectomy. The most likely mechanism is aberrant reinnervation of the sweat glands of the face by the severed parotid parasympathetic nerve fibers. A survey of 61 patients having undergone parotidectomy yielded 29 (47.5%) with gustatory sweating. Twenty-three percent (14 patients) considered the symptoms severe. In a double-blind study, five of those 14 patients were alternately treated with topically applied placebo and with glycopyrrolate (an anticholinergic agent) as 0.5% lotion, 2% lotion, and 2% cream. All five patients showed some improvement with the test preparations, but had longer lasting and more effective lessening of symptoms with the 2% glycopyrrolate preparations. There were no adverse side effects. We therefore believe that the topical application of a 2% glycopyrrolate preparation is a safe and effective treatment for severe gustatory sweating following parotidectomy.

Postoperative hypertension associated with radical neck dissection.

The incidence of hypertension following radical neck dissection was examined in 94 consecutive patients. Nine patients (9.6%) had postoperative blood pressure readings of 200/100 mm Hg or higher (n = 4) or of more than 40 mm Hg systolic and more than 20 mm Hg diastolic above preoperative levels (n = 5); ten patients (10.6%) had blood pressure readings of more than 40 mm Hg systolic or more than 20 mm Hg diastolic above preoperative levels. These elevations usually occurred in the first two postoperative hours and lasted approximately nine hours. Six patients required interventional therapy (intravenous nitroglycerin or sodium nitroprusside). No cardiac or central nervous system sequelae resulted, but two patients had postoperative hemorrhage and flap elevation by hematoma attributed to the hypertension. Carotid sinus denervation during radical neck dissection may be the cause of the reflex hypertension once general anesthesia-induced vasodilation has ended. Stripping of tumor from the carotid artery or placement of dermis grafts directly on the artery do not appear to influence postoperative development of hypertension.

Cold agglutinin disease in a patient with Legionnaires' disease.

We present a case of Legionnaires' disease complicated by cold agglutinin disease. Therapy with erythromycin gluceptate was associated with resolution of both the pneumonia and the hemolysis. Complement-fixing antibody levels to Mycoplasma pneumoniae, influenza A, and adenoviruses were measured repeatedly throughout the clinical illness and were persistently nondiagnostic. The cold agglutinin present in the patient's serum was characterized as an IgM that demonstrated anti-I specificity. Thus, Legionella pneumophila should be considered a potential causative agent in patients with pneumonia and cold agglutinin disease.