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Biomedical subjects

E Abemayor

Publications and source records attributed to E Abemayor.

15 recordsLinked to original sources
PubMed1992

Positron emission tomography: a new, precise imaging modality for detection of primary head and neck tumors and assessment of cervical adenopathy.

Positron emission tomography (PET) has been shown to be effective in detecting intracranial malignancies based on cerebral glucose metabolism. To evaluate the ability of PET to detect extracranial head and neck neoplasms and cervical metastases, 16 patients with primary squamous cell carcinomas were examined. All patients received preoperative computerized tomography (CT) and magnetic resonance imaging (MRI) scans and underwent PET evaluation using intravenous 18F-2-fluoro-2-deoxy-D-glucose (FDG). Histopathologic analysis compared tumor invasion and positive lymph nodes with findings on MRI, CT, and PET images. All primary tumors were delineated by PET, while MRI and CT failed to detect one superficial tumor involving the anterior tongue. Ten nodes were detected by CT and MRI versus 12 nodes demonstrated by PET. PET is highly effective in detecting head and neck carcinomas as well as metastatic cervical lymph nodes. In addition, PET may be useful in evaluating postsurgery and postradiotherapy patients for recurrent and new primary tumors.

Adult↗
PubMed1992

Nasopharyngeal carcinoma: treatment results with primary radiation therapy.

One hundred three patients with nasopharyngeal carcinoma were treated with radiotherapy at UCLA Medical Center from January 1955 to December 1990. Overall survival, disease-free survival, and local control rates were analyzed. In addition, survival from 1955 to 1978 and from 1979 to 1990 were evaluated. Overall 5- and 10-year actuarial survival rates for all patients were 58% and 47%, respectively. Disease-free survival rates at 3 and 5 years were 45% and 30%, respectively. Local, persistent, or recurrent disease in the nasopharynx was the primary cause of failure, occurring in 32% of patients and correlating with the initial tumor size (T stage). Twenty-four percent of patients developed distant metastases, which correlated with nodal status but not with T stage. Seventy-nine percent of patients failed either locally or distally by 4 years. Sex, race, age, and T and N stage categories were evaluated as prognostic variables in terms of survival. Control of primary disease is important in determining long-term outcome. Modern imaging techniques have greatly assisted in the evaluation of disease extent and treatment options.

Adolescent↗
PubMed1992

The effects of retinoic acid on the in vitro and in vivo growth of neuroblastoma cells.

In large part, malignancy is the end result of aberrant cell growth and differentiation. Control of these processes is anticipated to result in a suppression of oncogenicity. Retinoic acid (RA), a derivative of vitamin A, has been shown to inhibit proliferation, induce cell differentiation and reverse the malignant phenotype of a variety of tumor cell types. In order to further characterize the antitumor potential of RA, this study examined the in vitro and in vivo effects of this retinoid on cell lines derived from human neuroblastoma (NB). The in vitro phase of this study tested the ability of various compounds to raise intracellular cyclic adenosine 3':5'-monophosphate (cAMP) levels and either alone or in combination with RA, to promote differentiation of two relatively RA-resistant cell lines. Direct activation of the synthetic enzyme adenylate cyclase by forskolin or cholera toxin increased intracellular cAMP levels over 10-fold after 1 hour of treatment, declining over the next 16 to 24 hours. After 5 days of continuous growth in the presence of these agents, cAMP levels remained elevated 2- to 7-fold above control values and were accompanied by a decrease in cell proliferation and an increase in cell differentiation. All these effects were exaggerated in the presence of phosphodiesterase inhibitors. Isoproterenol and epinephrine did not alter cAMP levels and had no discernible biological effects. RA promoted differentiation with 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 treatment. From these data, it was concluded that: 1. the cAMP synthetic and degradative pathways are functional in the NB cell lines studied; 2. elevation of cAMP is a sufficient but not necessary condition for inhibiting proliferation and promoting differentiation in these cells; 3. elevation of intracellular cAMP potentiates the differentiation-inducing activity of RA; and 4. overcoming retinoid resistance in some tumor cell lines may be feasible by alterations in the cAMP system. This would be of particular value in treating tumors that have lost retinoid responsiveness. The in vivo phase of this study examined the effects of single-agent treatment using RA on the development and growth in nude mice of tumors derived from a NB cell line.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
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

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

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↗
PubMedDate not supplied

Burn of the auricle.

Silvadene cream and Sulfamylon make up the treatment regimen for one contributor (Dr. Crumley). No systemic antibiotics would be given. Any areas of obvious third-degree burns would be debrided and grafted. The tympanic membrane perforation would be treated with antibiotic/steroid drops. The second author concurs with use of Silvadene cream and would avoid any pressure on the area (Dr. Abemayor). While he agrees that systemic antibiotics should be avoided, he also would not prescribe ear drops. He recommends evaluation for a pulmonary or ophthalmologic injury. There is a disagreement regarding imaging studies. One expert would order a CT scan to rule out facial fractures (Dr. Crumley). His counterpart would not order a CT but would check a baseline chest x-ray if there were any sign of pulmonary compromise (Dr. Abemayor). Both experts would obtain an audiogram after the acute problems are treated. In the case of foul drainage, burn reconstruction would be delayed. In addition to treating the otorrhea with ear drops, one physician would add oral antibiotics (Dr. Abemayor). The other author believes tympanoplasty should be performed prior to reconstruction (Dr. Crumley). There were several procedures suggested for the reconstruction. Both authors discuss a method of creating a postauricular pocket, burying the ear pedicle, and using costal cartilage for an inlay helical graft. Another approach involves minimal debridement of the cartilage and letting the wound mature for 6 to 8 months. At that time the area would be debrided and the postauricular skin used for external coverage (Dr. Crumley). If the facial scar is a cosmetic problem 1 year after the injury, triamcinolone injections and local massage should be considered.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Tonsillectomy under local anesthesia: a safe and effective alternative.

Tonsillectomy using local anesthesia (local tonsillectomy) is a safe and effective alternative to general anesthesia in the healthy cooperative teenage or adult patient. This retrospective analysis involved 64 local tonsillectomies performed over the past 7 years in a minor operating room using only local anesthesia with intravenous sedation. Operations were performed by residents in training as well as by experienced head and neck surgeons. Blood loss, morbidity, complications, and patient satisfaction were reviewed and compared with tonsillectomies done under general anesthesia. The average blood loss was 42 mL in the local tonsillectomy group with no cases of postoperative hemorrhage, compared with 198 mL in the general anesthesia group with two cases of postoperative hemorrhage. There was one major complication related to postoperative antibiotic use in the local anesthesia group, and follow-up interviews revealed that patients were satisfied with the procedure and would recommend and choose local anesthesia again. We conclude that local tonsillectomies have high patient acceptance and are associated with minimal morbidity and complications. Furthermore, they are cost-effective.

Adolescent↗
PubMedDate not supplied

Tricholemmal cysts of the head and neck.

PURPOSE: Tricholemmal cysts, sometimes termed pilomatrixomas, are benign skin neoplasms. This study was undertaken to evaluate the clinical experience with management of pilomatrixomas at a large, referral-based university hospital. PATIENTS AND METHODS: The records of patients treated at the UCLA Medical Center were reviewed retrospectively. Patients treated during the years 1966 to 1991 inclusive were reviewed for details of the clinical course. All pathology slides were confirmed histologically. RESULTS: Pilomatrixoma was confirmed in 53 patients. Of these, 29 patients (55%) had pilomatrixoma isolated to the head and neck region. All were treated with surgical excision. One patient (3%) experienced recurrence due to inadequate initial excision. Subsequent re-excision resulted in a cure. CONCLUSION: Tricholemmal cysts present as solitary, painless, slow-growing cutaneous nodules often resulting in discoloration of the overlying skin. Simple excision cures this benign neoplasm, and recurrences are rare. Fine-needle aspiration biopsy may aid in the diagnostic workup.

Adolescent↗