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Biomedical subjects

L A Hoover

Publications and source records attributed to L A Hoover.

At least 19 recordsLinked to original sources
PubMed1999

Breed differences in deafferentation-induced neuronal cell death and shrinkage in chick cochlear nucleus.

Removal of functional presynaptic input can result in a variety of changes in postsynaptic neurons in the central nervous system, including altered metabolism, changes in neuronal cell size, and even death of the postsynaptic cell. Age-dependent neuronal cell death and shrinkage has been documented in second order auditory neurons in the chick brainstem (nucleus magnocellularis, NM) following cochlea removal (Born and Rubel, 1985. J. Comp. Neurol. 231, 435-445). Here we examined whether the extent of neuronal cell death and shrinkage is also breed-dependent. We performed unilateral cochlea removal on both hatchling and adult birds of either a broiler breed (Arbor Acres Cross) or egg layer breed (Hy-Line, H and N) and killed birds one week later. Changes in neuronal cell number and cross sectional area were determined from Nissl-stained sections. We observed 25% neuronal cell loss and a 15-20% decrease in neuronal cross sectional area after cochlea removal in either broiler or egg layer hatchling birds. In adult birds, however, neuronal cell loss is breed-dependent. Adult egg layer birds lose an average of 37% of NM neurons after cochlea removal, while adult broiler birds show no cell loss. In both breeds of adult birds, cochlea removal results in a 20% decrease in neuronal cross sectional area. These results suggest that analysis of differences between breeds as well as ages of birds will prove fruitful in determining how afferent input controls neuronal survival and metabolism.

Animals↗
PubMed1999

Characterization of cyclooxygenase in laryngeal papilloma by molecular techniques.

OBJECTIVES: Demonstrate the induction of cyclooxygenase-2 (COX-2) in laryngeal papilloma Discuss the possible causal role of COX-2 in papilloma formation. Consider the potential for treatment of papilloma using selective COX-2 inhibitors. STUDY DESIGN: Molecular biological analysis of COX-1 and COX-2 in laryngeal papilloma. METHODS: Tissue samples from five patients with recurrent respiratory papillomatosis (RRP) were analyzed by in situ hybridization, immunohistochemical staining, and reverse transcription polymerase chain reaction (RT-PCR) techniques. RESULTS: In situ hybridization to COX-2 mRNA showed strong autoradiographic signal surrounding fibrovascular cores. COX-1 autoradiographic signal was low intensity or nondetectable. Normal buccal mucosa biopsies showed low-density or nondetectable autoradiographic signal for both COX-1 and COX-2 mRNAs. In situ hybridization results were corroborated by RT-PCR studies. Levels of COX-2 mRNA were 13-fold more than those in normal mucosa. Immunohistochemical staining for COX-1 and COX-2 showed a similar pattern to that seen with in situ hybridization in both normal and papilloma tissues. CONCLUSIONS: There is an elevation of COX-2 expression in papilloma tissues. This may represent a causal role of COX-2 in the formation and proliferation of laryngeal papilloma. There may also be a role for selective COX-2 inhibition for the treatment of

Autoradiography↗
PubMed1995

Diagnosis and treatment of unilateral cricothyroid muscle paralysis with a modified Isshiki type 4 thyroplasty.

Cricothyroid adduction increases tension to the vocal folds, thus increasing fundamental frequency and upper pitch range. We treated 10 patients with cricothyroid muscle dysfunction using this technique. Preoperative electromyographic, acoustic, and perceptual analysis was performed. Intraoperatively the effect of increasing tension on the fundamental, falsetto, and basal frequencies was measured by using a strain gauge to the adducting suture at several tensions and a cervical microphone connected to a pitch meter. Postoperative acoustic and perceptual analysis was then performed up to 18 months later. Analysis of pitch vs. tension curves indicates a near-linear relationship until very high tensions are applied. Statistically significant improvement was achieved in both acoustic and perceptual analysis, although some deterioration was noted between early and late results. Cricothyroid adduction is indicated for a large range of vocal fold tension problems.

Acoustics↗
PubMed1990

Congenital muscular torticollis. A spectrum of disease.

Sternocleidomastoid muscle fibrosis has been recognized for centuries, but its pathogenesis and treatment remains controversial. Pseudotumor of infancy is a firm fibrous mass in the sternocleidomastoid muscle appearing at 2 to 3 weeks of age. Congenital muscular torticollis is less common and appears later in life. Pseudotumor and congenital muscular torticollis probably represent different manifestations of sternocleidomastoid muscle fibrosis. Pseudotumor will usually resolve with conservative therapy; however, some patients will subsequently develop torticollis. Congenital muscular torticollis usually requires surgical release of the sternocleidomastoid muscle to achieve a good cosmetic result and to prevent plagiocephaly, facial asymmetry, and scoliosis. This report provides guidelines for the management of congenital muscular torticollis and pseudotumor of infancy based on the authors' experience and review of the medical literature. Representative case histories from the neonate through the adult are presented, and the pathogenesis, diagnosis, treatment, and prognosis are discussed.

Adult↗
PubMed1990

Surgical strategy in thyroid disease.

Over the past 8 years, 311 patients have undergone surgical treatment by the senior authors for thyroid disease. Over 80% of the cases were performed by the head and neck surgical service at Olive View County Hospital, Sylmar, Calif, with the remainder performed at UCLA-affiliated institutions. This service is an important source of thyroid surgical training for UCLA head and neck residents who rotate through this major affiliate. The purpose of this communication is to review our experience with these cases; to describe our overall surgical strategy; and to detail the specifics of our surgical procedure, which we have developed to safely train residents in the treatment of these challenging cases. This article deals with the specific problems of preservation of the recurrent nerve, the parathyroid glands, and the techniques for reimplantation of injured parathyroid glands; the management of larger, substernal thyroid glands; and our techniques for partial thyroid surgery. In addition, the difficult decisions in the management of thyroid cancer, such as completion thyroidectomy; the management of lymph node mestastases; and how tracheal, esophageal, or laryngeal invasion should be managed are discussed. An initial section describing the general preoperative examination of these patients is also included, so that the proper surgical strategy can be developed prior to entering the operating room.

Adult↗
PubMed1988

Physiologic exclusion of the injured esophagus.

Despite continuing advances in the surgical and nutritional management of esophageal perforation, morbidity and mortality remain significant. Described within is the successful management of two such cases by the physiologic exclusion of the esophagus. By this, we mean distal decompression and proximal diversion and decompression through a gastrostomy and cervical esophagostomy. This provides the greatest chance for protection of the esophageal suture line repair.

Aged↗
PubMed1988

Autotransplantation of parathyroid tissue into sternocleidomastoid muscle.

Four cases of secondary hyperparathyroidism were treated by total parathyroidectomy with autotransplantation into the sternocleidomastoid muscle. These total parathyroidectomy patients are presented to demonstrate the reliability of parathyroid autotransplantation into the sternocleidomastoid muscle. Our technique is described in detail, and all procedures were successful. In one case, the patient was found, in retrospect, to have an adenoma in the transplanted parathyroid tissue. When the patient developed graft-dependent hypercalcemia, a portion of the graft was easily excised under local anesthesia and the patient became normocalcemic. Parathyroid tissue should be transplanted into the sternocleidomastoid muscle rather than other sites because of easy accessibility, one operative site, less graft ischemia, a low incidence of infection, and a high success rate due to excellent blood supply.

Adult↗
PubMed1988

Stabilization of hearing loss in Paget's disease with calcitonin and etidronate.

Paget's disease is a common skeletal disease characterized by abnormal bony resorption and deposition. Although the disease principally affects the axial skeleton, skull and temporal bone involvement occur. Affected individuals have significantly different rates of progression of hearing loss than normal persons. We describe two patients in whom this progressive hearing loss was halted and even reversed. These patients were treated with calcitonin and etidronate disodium and have been followed up for five and 3 1/2 years, respectively. Computed tomographic scans demonstrating extent of disease are included along with our treatment regimen and alkaline phosphatase response curves.

Aged↗
PubMed1988

Polyarteritis nodosa involving only the main renal arteries.

A unique case of accelerated hypertension and acute anuria in a 24-year-old man is presented. Clinically, the patient was found to have obstruction of both main renal arteries caused by extensive bilateral thrombosis. Microscopically, a healing panarteritis involving only the main renal arteries was found. This was associated with acute renal infarction and tubular atrophy in the left kidney. This appears to be an unusual variant of polyarteritis nodosa limited to both main renal arteries.

Adult↗
PubMed1988

Vertigo in the hyperviscosity syndrome.

Diseases that cause hyperviscosity of the blood can result in otologic symptoms--especially vertigo. These symptoms are predominantly produced by peripheral vestibular involvement. The pathophysiology probably involves vascular obstruction in the venules. Specific changes in the microvasculature are presumed to be comparable to those that occur with hyperviscosity disorders in the retina. Maintenance of a normal blood viscosity will prevent damage to the ear, as well as other organs. Additionally, reduction of the blood viscosity can greatly improve otologic symptoms. Case studies and a review of the pertinent literature are included.

Adult↗
PubMed1987

Staging of base of tongue carcinoma by computed tomography.

Staging of carcinoma of the base of the tongue according to the system adopted by the American Joint Committee on Cancer relies on clinical examination possibly augmented by multiple biopsies. Palpation of the tongue base can be difficult without anaesthesia due to retching and vomiting. Computed tomography can, however, accurately depict the deep structures of the base of the tongue without discomfort to the patient. It can also demonstrate the nodal stations of the neck. In 12 patients with primary carcinoma of the base of the tongue the clinical staging results were compared with the CT findings. In 10 of the 12 patients there was good correlation between tumour size and location, while only 2 patients showed a 1.0-1.5 cm discrepancy in the size estimate of the primary tumour. A total of 9 enlarged lymph nodes or nodal groups were only found by CT. The majority of positive nodal stations demonstrated only by CT were in the contralateral neck. Computed tomography is a valuable complement when staging tongue base carcinomas, particularly when evaluating the neck for lymph node metastasis.

Carcinoma↗
PubMed1987

Magnetic resonance imaging of the larynx and tongue base: clinical applications.

The use of surface coils on subjects, and internal engineering improvements have combined to greatly improve the signal-to-noise ratio on the magnetic resonance imager at our institution over the past two and one-half years. This has resulted in a marked improvement in image resolution, as well as reduction in the time required and related cost of these studies. Magnetic resonance (MR) examinations at our institution now cost less than comparable computed tomography (CT) studies. This article summarizes our experiences in imaging the larynx and tongue base. Eleven cases are presented to illustrate how the direct multiplane capacity of MRs and their increased soft tissue contrast provide some definite advantages over CT in determination of extent of disease in these regions.

Aged↗
PubMed1986

A systematic approach to parathyroid surgery.

In the last 8 years 33 patients with hyperparathyroidism have been surgically treated by the authors. Thirty patients had primary, 2 secondary and 1 tertiary hyperparathyroidism. In the 30 patients with the primary disorder, 26 had a single adenoma and 28 of these patients had normal calcium levels postoperatively. Two patients were hypocalcaemic following surgery and required calcium supplements for 3 months and 9 months respectively. It is recommended that when a single adenoma is found its removal will render the patient normocalcaemic. When all 4 glands are hyperplastic the surgery should be subtotal (3 1/2 glands) parathyroidectomy except in the case of secondary hyperparathyroidism when total parathyroidectomy with autotransplantation and cryopreservation of the remainder should be performed.

Adenoma↗
PubMed1986

Tongue and oropharynx: findings on MR imaging.

Ten healthy subjects and 44 patients with diseases of the tongue or oropharynx were studied with magnetic resonance (MR) imaging. Axial, coronal, and sagittal images with a thickness of 4 mm were obtained with a pixel size of 0.75 X 0.75 mm on a 256 matrix. Nineteen of the patients underwent computed tomography (CT). Nine of those patients later had surgery, and the specimens were obtained for organ sectioning. These three studies as well as clinical history and physical examination findings were correlated. MR imaging was equal to or better than CT in those patients having both examinations. However, neither CT nor MR allowed recognition of histologic features or detection of microscopic spread of disease. Direct coronal and sagittal imaging planes on MR imaging allowed visualization of intrinsic tongue musculature, not possible with CT; this was important in recognizing subtle tumor extension. For these reasons, MR is the imaging method of choice for studying diseases of the tongue and oropharynx.

Adult↗