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Biomedical subjects

R R Gacek

Publications and source records attributed to R R Gacek.

At least 55 records · Page 3Linked to original sources
PubMed1989

Actomyosin adenosine triphosphatase activities of the cat infrahyoid muscles.

By use of actomyosin ATPase histochemistry, it was found that there were large differences among the three cat infrahyoid muscles (sternohyoid, sternothyroid, and thyrohyoid) with respect to their percentages of different muscle fiber types. It has been established that the individual activity patterns of the component motor units in each muscle drive the biochemical and physiologic differentiation of the muscle fibers associated with each motor unit. Therefore, the data obtained in the present investigation provide an indication of the characteristics of long-term use of each of the various types of motor units, as well as the associated differences in the physiologic capacities of the different motor unit types composing each of these infrahyoid muscles.

Animals↗
PubMed1989

Morphologic correlates of vestibular compensation in the cat.

Vestibulo-ocular (VO) neurons in the superior vestibular nucleus (SVN) were labeled with horseradish peroxidase (HRP) and studied quantitatively in the electron microscope to determine the morphologic correlates of vestibular compensation. Eighteen cells from four normal cats were compared to 26 cells from four 8-week vestibular neurectomy animals and 29 cells from four 1-year neurectomy animals. There was a greater than 70% decrease in synaptic profiles (SP) on the VO soma in both experimental groups. Increased excitatory activity in the residual SP are indicated by (1) smaller synaptic vesicles (SV) with increasing survival after neurectomy, (2) the association of the SP with a higher ratio of asymmetric to symmetric synapses, and (3) a higher volume fraction of mitochondria in the SP. The experimental VO soma showed a 17% reduction in size (cytoplasm), and a decrease in rough endoplasmic reticulum and polyribosomes. The target cell also showed an increased number of somal spines associated with the remaining SP in the 1-year neurectomy group.

Animals↗
PubMed1988

Ultrastructure of contralaterally projecting vestibular efferent neurons in the cat.

Numerous reports have demonstrated that primary vestibular afferent axons terminate in the vicinity of centrally located vestibular efferent (VE) neurons. The goal of this study was to morphologically demonstrate contact of primary vestibular afferents directly on the soma of contralaterally projecting VE neurons, as well as develop a quantitative description of these neurons. A right vestibular neurectomy was performed in three young adult cats followed up three days later by the placement of horseradish peroxidase into the left vestibule. Labeled contralateral (right) VE neurons were examined in a transmission electron microscope for degenerating synaptic profiles contacting the soma. Ultrastructural characteristics of VE neurons, including nuclear size, volume fraction of intracellular organelles, number of synaptic profiles, and cellular shape, were quantitatively analyzed. No degenerating synaptic profiles were observed on labeled VE soma, although degenerating axons were present nearby. Statistical analysis of volume fraction data of the VE neurons suggests a continuum of a single subpopulation of cells rather than multiple subpopulations.

Animals↗
PubMed1987

Motor end-plate distribution in the human interarytenoid muscle.

Histochemical and computer graphic techniques were used to determine the distribution of neuromuscular junctions in the human interarytenoid (IA) muscle. The motor end-plates of four IA specimens obtained from normal postmortem larynges were visualized using an acetylcholinesterase stain. The three-dimensional distribution of motor end-plates was later reconstructed using computer graphics. The motor end-plates in the IA were found to be distributed in an inverted "Y" configuration. A broad band of end-plates was found at the midpoint of the muscle fibers in the superior and middle aspect of the muscle. This band divided obliquely in a lateral direction toward the inferior border of the muscle. This pattern of motor end-plate distribution is possibly consistent with the bilateral innervation of the IA by the recurrent laryngeal nerves.

Adult↗
PubMed1987

The temporal bone anomaly in CHARGE association.

Examination of the temporal bones from a patient with the CHARGE association revealed an unusual form of dysplasia. Mondini dysplasia of the pars inferior with complete absence of the pars superior was observed in both temporal bones. A review of the literature revealed four previous descriptions of this unique anomaly in patients whose clinical picture resembled the required components of CHARGE. On this basis, it is suggested that this anomaly represents a specific form of labyrinthine dysplasia which may be called the CHARGE dysplasia of the temporal bone.

Abnormalities, Multiple↗
PubMed1987

Esterase activity in cat vestibular end organs. An enzymatic barrier system?

A series of highly specific inhibitors and substrates were used to specifically characterize the esterases present in the five vestibular end organs (the three semicircular canal cristae, the utriclar, and the saccular macula) from four young adult cats. No butyrylcholinesterase or nonspecific acetylcholinesterase activity was found. The results indicate a dense localization of acetylcholinesterase activity beneath and between the hair cells, at the sensory epithelial and subepithelial junction, and within vascular elements. This reaction product extends along the entire length of the sensory epithelium. Activity also extends proximally to the areas of the nerves' entrance into the subepithelial tissue. It should be noted that most of the activity is likely to be located in the extracellular matrix, as well as in the endoneurium. This extracellular distribution may represent an enzymatic barrier to the diffusion of acetylcholine that may be essential for the normal function of the end organ and possibly similar to the blood-brain barrier in some respects.

Acetylcholinesterase↗
PubMed1986

Motor end-plate distribution in the human lateral cricoarytenoid muscle.

Knowledge of the neuromuscular junction distribution in the intrinsic laryngeal muscles has potential clinical application in directing procedures that affect the function of these muscles through their neuromuscular junctions. We used histochemical techniques and computer graphics to determine the three-dimensional distribution of the motor end-plates in the human lateral cricoarytenoid muscle. In contrast to the results that have been reported for the human thyroarytenoid, cricothyroid, and posterior cricoarytenoid muscles, where end-plates are more diffusely distributed, the results of our study indicate that in the human lateral cricoarytenoid muscle, the neuromuscular junctions are generally found within a broad band at the midlength of the muscle. This more focused distribution should be advantageous clinically in facilitating the manipulation of the motor end-plates in this muscle.

Acetylcholinesterase↗
PubMed1986

Anatomical investigation of the corticonuclear projections to the facial nerve nucleus in the cat.

The present study was performed to demonstrate a cortical projection to the facial nucleus of the cat. The right facial nucleus of 16 cats was injected with the retrograde tracer horseradish peroxidase (HRP). After allowing 36 hours for the retrograde transport of HRP, the animals were sacrificed by perfusion. The cortex, midbrain, and brain stem were removed, frozen sectioned, and reacted for HRP activity. Labeled pyramidal type cells were found bilaterally in layer V of the anterior sigmoid, presylvian, and coronal gyri of the frontal cerebral cortex. A significantly greater number of labeled cells were present in the contralateral motor cortex. Labeled cells were also found in the contralateral red nucleus, ipsilateral oculomotor nucleus, and periaqueductal gray substance of the midbrain.

Animals↗
PubMed1985

Three-dimensional distribution of neuromuscular junctions in human cricothyroid.

Microinjections of myoneural blocking agents are effective in the treatment of strabismus and have been proposed as a possible technique to treat spastic dysphonia. The success of such a technique would rely on a precise knowledge of the neuromuscular junction distribution in the laryngeal muscle to be injected. In view of the possibility of an involvement of the cricothyroid muscle in spastic dysphonia or other neuromuscular disorders, we determined the three-dimensional distribution of neuromuscular junctions in the human cricothyroid muscle. Cricothyroid muscles obtained from autopsy cases were fixed, sectioned, and processed for the histochemical localization of neuromuscular junction acetylcholinesterase. Using serial sections and a computer interfaced X-Y digitizer, the neuromuscular junctions were referenced to various anatomic landmarks and the neuromuscular junction distribution and reconstructed in three dimension using computer graphics.

Computers↗
PubMed1985

Anatomic organization of the cat facial nerve.

The location of efferent neurons supplying muscles innervated by the facial nerve was studied in the brain stem of the cat; horseradish peroxidase (HRP) was used as a tracer of retrograde protein transport. One to 15 microliters of HRP was injected into various muscles. Orbicularis oculi and orbicularis oris muscles were represented in the lateral division of the facial nucleus. The platysma, posterior belly of digastric, auricularis superior, and frontalis muscles were represented in the medial division of the facial nucleus. No labeled neuron was found in the trigeminal nerve nucleus or any other brain stem nuclei. The grouping of the motor neurons into relatively discrete areas of the nucleus and the fact that the facial nerve innervates various muscles through separate branches suggest that these motor neurons travel together in discrete groups within the facial nerve trunk. However, orientation of the facial nerve fibers was demonstrated by use of the Marchi method and an osmium stain after complete and partial transection of the nerve at the internal auditory meatus; this showed that the motor axons to the peripheral branches are diffusely located throughout the temporal course of the facial nerve.

Animals↗
PubMed1985

Three-dimensional computer reconstruction of the neuromuscular junction distribution in the human posterior cricoarytenoid muscle.

Recent studies have indicated that in a denervated muscle highly specific interactions occur between regenerating axons and the basal lamina of the myofiber precisely at the original synaptic sites. Since these findings suggest that synapse regeneration is facilitated at the original synaptic sites, a knowledge of the distribution of neuromuscular junctions in the human posterior cricoarytenoid (PCA) muscle may guide reinnervation procedures in this muscle. We, therefore, have used histochemical and computer graphics techniques to reconstruct the three-dimensional distribution of neuromuscular junctions in the human PCA taken fresh at autopsy. The results indicated a more localized pattern of neuromuscular junctions as compared to the human thyroarytenoid muscle. The results will be discussed with respect to their implications for procedures for reinnervation of the posterior cricoarytenoid muscle.

Computers↗
PubMed1985

Left neck mass.

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Head and Neck Neoplasms↗
PubMed1984

Non-Hodgkin's lymphoma limited to the larynx.

A case of primary laryngeal non-Hodgkin's lymphoma is detailed, with a review of the reports in the English literature on this rare site of presentation. Symptoms at onset generally include hoarseness, and may be observed up to 60 months prior to diagnosis. Four of the five cases classified by the Rappaport system are of diffuse histology. The histologic distinction of true lymphoma from pseudolymphoma, which may mimic lymphoma both grossly and microscopically, is reviewed. Local radiotherapy is a curative treatment of choice, with 16 of 18 cases disease-free throughout follow-up.

Aged↗
PubMed1984

Local excision and radiotherapy for cancer of the oral tongue. A preliminary report.

A group of 18 patients with squamous cell carcinoma of the mid one-third of the tongue was treated by local resection and planned postoperative radiotherapy between 1976 and 1980. Tumors 0.5 cm or greater in thickness were included; no patients had cervical adenopathy. Six were categorized as T1, 10 as T2 and two as T3. In eight patients, histologic review showed tumor extension at or near the resection margin, despite a tumor-free margin at frozen section, while in 10 patients the margins were clear. Local tumor control was achieved in 16 patients (89%). Two failures were evident within 3 months after completion of treatment. The relatively short follow-up of such a small series limits the conclusions from this preliminary study, but the excellent results thus far merit further study.

Adult↗