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Biomedical subjects

E Abemayor

Publications and source records attributed to E Abemayor.

At least 37 records · Page 2Linked to original sources
PubMed1991

Slide presentation graphics using a personal computer. A comparative evaluation of available software.

Most of the available methods for preparing professional slides to be used in oral presentations can be cumbersome, time-consuming, and expensive. Creating high-quality 35-mm slides may require the use of expensive medical illustrators and photographic equipment not available to all physicians. More recently, technology has emerged that permits professional in-office generation of quality slides using commercially available computer graphics software and film recorders. Such a system is simple to establish and maintain when compared with commercial slide production facilities. We will review the hardware requirements of such a system, as well as the advantages and disadvantages of several commercially available software packages. Using a personal computer-based slide-making system, any physician communicating with small or large groups of people can now produce professional-looking slides easily, rapidly, and inexpensively.

Audiovisual Aids↗
PubMed1991

Malignant nerve sheath tumors of the head and neck: a combined experience from two university hospitals.

Malignant schwannoma is an aggressive neoplasm whose cell of origin and histologic characteristics remain controversial. Despite advances in diagnostic techniques, the natural history of this tumor remains uncertain. The charts of all patients with malignant schwannoma who were treated at the UCLA Center for the Health Sciences and the University of Iowa Hospital and Clinics were retrospectively reviewed. Sixteen patients received surgery and radiotherapy in combination or as sole therapy. Irrespective of treatment modality, prognosis was poor with an overall survival of 15%. Recent advances in imaging and histologic techniques that assist in establishing the diagnosis and delineating tumor location are discussed. In addition, the literature pertaining to malignant schwannoma of the head and neck is reviewed.

Adolescent↗
PubMed1990

Effects of retinoic acid on the in vivo growth of human neuroblastoma cells.

We have investigated the effects of retinoic acid (RA) on the development and growth in nude mice of tumors derived from the human neuroblastoma cell line LA-N-5. When cells were treated with 4 x 10(-6) M RA in vitro there was a marked reduction in the number of mice developing tumors when compared to solvent-treated controls. In vivo treatment with RA reduced tumor formation when the retinoid was given for 5 days before tumor injection and continued for 14 days thereafter. In established tumors, RA inhibited progressive tumor growth. There was no demonstrable effect of RA in vivo on the morphologic phenotype of the tumor cells when these regimens were used. We conclude that oral retinoid administration may prove useful in inhibiting or arresting the growth of neuroblastoma, particularly when there is a small initial tumor burden.

Animals↗
PubMed1990

Modulation of intracellular cyclic adenosine monophosphate levels and the differentiation response of human neuroblastoma cells.

We have tested the ability of various compounds to raise intracellular cyclic AMP (cAMP) levels and, either alone or in combination with retinoic acid (RA), to promote differentiation of two "RA-resistant" sublines of LA-N-5 human neuroblastoma cells, designated LA-N-5HP and LA-N-5R9. Direct activation of adenylate cyclase by forskolin and cholera toxin increased intracellular cAMP levels over 10-fold in both cell lines after 1 h of treatment, after which the levels slowly declined for the next 16 to 24 h. After 5 days of continuous treatment, cAMP levels still remained 2- to 7-fold elevated above controls and were accompanied by a decrease in cell proliferation and an increase in neurite outgrowth. All these effects were exaggerated when the agents were combined with phosphodiesterase enzyme inhibitors. Increasing cAMP levels (up to 24-fold) with N6,O2'-dibutyryl cyclic AMP (dbcAMP) or 8-bromo-cAMP also resulted in decreased proliferation and an increase in morphological differentiation. Isoproterenol and epinephrine did not alter cAMP levels and had no discernible biological effects. Of the agents that raised cAMP levels, only dbcAMP caused an increase in acetylcholinesterase activity. This effect was duplicated with sodium butyrate and prostaglandin E1 in the absence of an increase in cAMP. RA promoted differentiation but also had little effect on cAMP levels. Combination treatment of cells with RA plus agents that raised cAMP levels resulted in greater degrees of differentiation than seen with single agent treatments. We conclude that: (a) the cAMP synthetic and degradative pathways are functional in LA-N-5HP and LA-N-5R9 cells; (b) elevation of cAMP is sufficient for inhibiting proliferation and promoting neurite outgrowth from these cells, but is not a necessary condition for inducing differentiation; and (c) elevation of intracellular cAMP potentiates the differentiation-inducing activity of RA.

Acetylcholinesterase↗
PubMed1990

Occult primary tumors. The management of isolated submandibular lymph node metastases.

The management of patients with cervical metastases from unknown primary tumors presents a therapeutic challenge to both the head and neck surgeon and radiotherapist. If after careful search the primary tumor remains truly occult, traditional methods of radiotherapy encompassing fields from the base of skull to clavicles are often employed, with significant attendant morbidity. To determine if more limited therapy would be effective in cases of isolated regional lymph node metastases, the patterns of tumor spread to nodes in the submandibular region were studied. A retrospective analysis of 472 radical neck specimens obtained from 1975 to 1985 revealed 19 cases (4.0%) of cervical metastases limited to the submandibular triangle. Sources of these tumors included lip (3), buccal mucosa (4), nasal vestibule (1), floor of mouth (4), alveolar ridge (3), oral tongue (1), and unknown (3). It appears that solitary submandibular nodal metastases predominantly arise from sites in the oral or nasal cavity. This suggests that in patients with isolated submandibular lymph node metastases from occult primary sites, a more conservative therapeutic approach to potential primary sites is indicated after treatment of the metastatic focus.

Adult↗
PubMed1990

Evaluation of mandibular tumor invasion with magnetic resonance imaging.

Evaluating the extent of tumor invasion of the mandible is clinically important in the management of mandibular tumors. Conventional imaging studies including panoramic radiography, bone scans, and computed tomography, as well as clinical evaluation can be unreliable in defining the extent of neoplastic marrow invasion. This study presents the initial UCLA, Los Angeles, Calif, experience with magnetic resonance imaging in evaluating mandibular invasion by benign and malignant neoplasms. Magnetic resonance imaging, using T1 and T2 images, was compared with conventional imaging methods in 11 patients with malignant lesions and nine patients with benign lesions. In all cases, magnetic resonance imaging most accurately determined the full extent of tumor invasion in the mandibular marrow spaces. Magnetic resonance imaging appears to be superior to offer clear benefits over conventional imaging methods, including computed tomography, for the evaluation of tumor invasion of the mandible.

Adult↗
PubMed1989

Parotitis and facial nerve dysfunction.

Paralysis of the facial nerve in association with suppurative parotitis is rare, with only ten previously reported cases. In some situations, inflammation surrounding a benign neoplasm accounted for the observed paralysis. In this article, three new cases of parotitis with associated facial nerve dysfunction are described, none of which was associated with a neoplasm. In one, an occult abscess was present and in another an aggressive necrotizing process was seen. The treatment of this disease should initially be conservative management with high doses of wide-spectrum antibiotics. In the majority of cases, resolution of the facial paralysis should follow. However, persistence of a parotid mass with continued facial palsy mandates surgical exploration to exclude the presence of an underlying neoplasm.

Adult↗
PubMed1989

Human medullary thyroid carcinoma. Initial characterization and in vitro differentiation of two new cell lines.

Medullary carcinoma of the thyroid (MCT), a tumor of calcitonin (CT)-secreting C cells, can display a variable malignant potential with poor prognosis linked to decreased cell differentiation. In vitro study of MCT has been hampered by the fact that few cell lines derived from this neoplasm have been available for study. Herein are reported the characteristics of two new lines derived from human MCT that are tumorigenic in athymic mice and do not secrete CT. After treatment with various concentrations of retinoic acid (a vitamin A derivative) and cyclic adenosine monophosphate, both lines exhibit the traits of more differentiated cells with a decrease in cellular proliferation and an increase in cytoplasmic CT content as shown by in situ immunoperoxidase staining. These cell lines should prove of great value in the study of the biology of MCT and the mechanisms underlying induced differentiation in this type of tumor.

Animals↗
PubMed1989

MRI of the mandible.

Eighteen patients with abnormalities of the mandible and two normal volunteers were studied with MRI. Correlation was made with MR, CT, plain X-rays, clinical examination, and surgical findings when possible. In primary tumors of the mandible, MR was able to differentiate between solid and cystic lesions. In the cases of secondary invasion of the mandible by malignant tumors, MR was able to demonstrate replacement of the normal high signal bone marrow by low signal tumor. In some cases, the extent of marrow involvement shown on MR and confirmed at surgery was significantly underestimated by clinical examination, plain films, and CT. From this limited experience, it appears that MR may play an important role in imaging pathology of the mandible.

Humans↗
PubMed1989

Human neuroblastoma cell lines as models for the in vitro study of neoplastic and neuronal cell differentiation.

Neuroblastoma is a childhood solid tumor composed of primitive cells derived from precursors of the autonomic nervous system. This neoplasm has the highest rate of spontaneous regression of all cancer types and has been noted to undergo spontaneous and chemically induced differentiation into elements resembling mature nervous tissue. As such, neuroblastoma has been a prime model system for the study of neuronal differentiation and the process of cancer cell maturation. In this paper we review those agents that have been described to induce the differentiation of neuroblastoma, with an emphasis on the effects and possible mechanisms of action of a group of related compounds, the retinoids. With this model system and the availability of subclones that are both responsive and resistant to chemically induced differentiation, fundamental questions regarding the mechanisms and processes underlying cell maturation have become more amenable to in vitro study.

Butyrates↗
PubMed1989

Preservation of hearing in cholesteatomas with inner ear invasion.

Two cases of inner ear destruction by cholesteatoma are presented. There was total demineralization of the cochlea in one and significant vestibular destruction in the other. Eradication and exteriorization of the disease was accomplished with preservation of hearing in both cases. Safe management was enhanced by aggressive infection control and accurate surgical planning aided by current imaging techniques. The factors which protect auditory function in these lesions remain unclear. However, the site and extent of the disease as well as local tissue reaction leading to separation of the inflammatory process from the sensory epithelium appear to play a significant role in preservation of hearing despite the presence of invasive, destructive disease.

Adult↗
PubMed1988

Granulocytic sarcomas of the head and neck.

Granulocytic sarcomas (chloromas) are rare tumors with a predilection for head and neck sites. In a review of six cases from two teaching institutions, chloromas were associated with the development of acute myelogenous leukemia or a relapse in five cases. Treatment modalities included chemotherapy and radiation therapy for problematic lesions. Our only survivor received combination therapy despite a negative bone marrow examination. Work-up should include a computed tomographic scan or magnetic resonance imaging to evaluate the extent of the tumor. Bone marrow examination and biopsy should be performed and specimens prepared for immunohistochemical studies or electron microscopy. Recommended treatment includes both aggressive chemotherapy and 2000 to 3000 cGy of external-beam radiotherapy to the tumor when possible.

Adolescent↗
PubMed1988

Identification of synchronous esophageal tumors in patients with head and neck cancer.

Patients with a primary head and neck neoplasm are at risk for additional malignancies of the upper aerodigestive tract, which may be asymptomatic. This phenomenon may reflect the regional carcinogenic influence of alcohol and tobacco abuse. A review of the recent literature documents the value of performing laryngoscopy, bronchoscopy, and esophagoscopy on all patients being staged for head and neck tumors to identify second synchronous cancers, the presence of which may significantly alter the treatment plan.

Aged↗
PubMed1988

Cystosarcoma phyllodes metastatic to the mandible.

Cystosarcoma phyllodes of the breast appears to encompass a diverse group of tumors with variable clinical behaviors. Although the tumor can behave in a malignant fashion, metastases to the head and neck region are distinctly uncommon. A case is presented of a solitary metastasis to the mandible appearing 1 year after mastectomy and in the absence of widespread disease. The metastatic potential of this neoplasm is discussed and involvement of the head and neck region is reviewed.

Breast Neoplasms↗
PubMed1988

The transoral treatment of mandibular fractures using noncompression miniplates: a prospective study.

A prospective study was performed to evaluate the efficacy of noncompression miniplates in the repair of mandible fractures treated at a large regional trauma center. The study included 54 cases of all types of adult mandible fractures with the exception of fractures of the condylar neck and ascending ramus. Cases were excluded in which preexisting infection was present. The technique consisted of a transoral approach followed by monocortical juxtaalveolar and subapical osteosynthesis without long-term intermaxillary fixation. Overall, there were 7 complications associated with this technique (13%): 4 infections (7.4%), 1 malunion (1.9%), and 2 mental nerve paresthesias (3.7%). These results compare favorably with those reported in the literature and suggest that mandibular osteosynthesis using miniature malleable plates is a useful and effective method for the repair of selected mandible fractures.

Adolescent↗
PubMed1988

Juvenile nasopharyngeal angiofibroma: an update of the UCLA experience, 1960-1985.

The UCLA experience with juvenile angiofibroma (JNA) over a 25-year period is reviewed. There were 83 patients, the majority being adolescent males. Surgery was the primary method of treatment for disease not extending intracranially; 63 of 68 patients (92.5%) became asymptomatic with this modality. In patients treated with a single course of primary radiation, 10 of 14 (78.5%) became asymptomatic. Trends in diagnosis and treatment were evaluated. Contrast computerized tomography reliably assesses tumor extent. Preoperative arteriography is essential for the evaluation and embolization of feeding vessels; this in turn significantly reduces operative blood loss and the need for transfusions. Radiotherapy should be reserved for disease extending intracranially and should be in doses of 3,600 cGy or larger.

Adolescent↗