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Biomedical subjects

L D Lowry

Publications and source records attributed to L D Lowry.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Experimental motion sickness induced in squirrel monkeys by continuous off-axis horizontal rotation.

Under a variety of experimental conditions, nonrestrained adult male squirrel monkeys were subjected to continuous rotation in the horizontal plane at 33 rpm. Severity of motion-induced sickness was quantified by measuring latencies of three responses associated with sickness. Per- and postrotational nystagmus was recorded from a subsample of monkeys with permanent recording electrodes implanted in the bony orbits. Incidence of sickness depended on the time limits of stimulation imposed, and it occurred in a maximum of about 90 per cent of test sessions if rotation was continued for two hours. When subjected to ten once-per-day rotation sessions, only a few monkeys showed evidence of developing transient habituation of onset of motion sickness. Mean frequency of emetic episodes, however, declined over the latter half of the rotation series. Restricting visual cues by blindfolding the monkeys prevented most subjects from vomiting.

Animals↗
PubMedDate not supplied

Behavioral conditioning and experimental motion-induced sickness.

Adult male squirrel monkeys were the subjects of experiments conducted to determine whether or not repeated exposures to sickness-inducing horizontal rotation would result in behavioral conditioning of emetic responses. The development of conditioned food aversion and feeding suppression as a consequence of pre- and postrotation eating was quantified. It was concluded that neither instrumental conditioning nor classical conditioning were valid alternative hypotheses for the occurrence of repeated vomiting episodes over a period of ten daily exposures to motion. Conditioned aversion to fresh banana and feeding suppression developed gradually if rotation, which induced multiple bouts of vomiting, was sustained for 1- or 2-hour sessions. If spinning was terminated immediately after the first emetic response, no aversion or suppression emerged. The occurrence of food aversion, by itself, is questioned as a valid index of the presence of subjective concomitants of motion sickness in animals.

Animals↗
PubMedDate not supplied

Effects of hyperosmotic solutions on endolymphatic pressure.

Hydrostatic pressure changes in endolymph as well as perilymph and cerebrospinal fluid (CSF) following intravenous injection of glycerol, urea, and mannitol were studied in the guinea pig using a servo-controlled micropipet system. After the initial rise in pressure observed during and immediately after injection of each hyperosmotic agent, all pressures fell below baseline levels for about 20 minutes. The largest reductions in pressure with each of the hyperosmotics showed no significant difference between CSF and labyrinth. In the glycerol and urea studies, labyrinthine pressures stabilized at their minimum levels 20 to 40 minutes after injection, while CSF pressure recovered slowly. However, alteration of labyrinthine pressures induced by mannitol paralleled that of CSF. These results may suggest a possible osmotic dehydration effect in the labyrinth for glycerol and urea, but an ambiguous effect for mannitol.

Animals↗
PubMedDate not supplied

A two-factor model of rotation-induced motion sickness syndrome in squirrel monkeys.

Nonrestrained squirrel monkeys were rotated repeatedly in the horizontal plane once per day for preset times or until a vomiting response occurred. Emesis latencies and frequencies were recorded. Some subjects were fed fresh banana immediately before and after each rotation. The amount consumed provided a measure of conditioned food aversion or feeding suppression. A two-factor model of the motion-sickness syndrome was formulated to account for the data. According to the model, appropriate stimulation of the semicircular canals accompanied by visual and proprioceptive stimulation generates two independent physiologic processes or states: an objective emesis and a subjective nausea process. The emesis process is revealed by vomiting responses and the nausea process is inferred from the appearance of conditioned food aversion. Susceptible monkeys (type I) and resistant monkeys (type II) have different emesis processes, but both have similar nausea processes. Refractory monkeys have no well-developed emesis or nausea processes. Time and order characteristics of the motion-sickness syndrome depend on specific interactions of emesis and nausea processes.

Animals↗
PubMedDate not supplied

Teflon paste implant in unilateral vocal cord paralysis: CT characteristics.

Laryngeal Teflon paste implants are routinely used to lessen the manifestations of unilateral vocal cord paralysis. Although the Teflon paste is not visible on plain radiography, it is detected on CT as a high density area. Computed tomography may be useful as a baseline study to determine the amount and location of the Teflon paste and also to detect complications such as acute edema, migration of paste, or chronic granuloma formation.

Adult↗
PubMedDate not supplied

Study of 100 patients with bilateral sensorineural hearing loss for lipid abnormalities.

One hundred persons were selected from our audiology records who showed at least 20 dB bilateral sensorineural hearing loss. The number 100 was picked for an adequate statistical analysis. The patients were taken from the chart files which are filed in chronological order. Letters were mailed with instructions for fasting 14 hours prior to testing except for the consumption of water. On presentation, a history was taken for diabetes, height and weight, and the blood pressure was recorded. The blood samples were drawn in clot tubes and taken to a commercial laboratory for overnight refrigeration and testing of the serum. Testing included observation of serum for massive chylomicronemia, triglycerides, cholesterol and lipoprotein electrophoresis (by the cellulose acetate method). Lipoprotein testing results showed 12 patients with Type II A or II B and 8 patients with Type IV abnormalities. No Types I, III or V were found. These 20 patients represent a lower number of hyperlipoproteinemic patients than would be expected in the general population.

Aged↗
PubMedDate not supplied

Aortic arch anomalies in adult disorders of deglutition.

Congenital vascular anomalies of the aortic arch are unusual etiologies of dysphagia in the adult. Swallowing abnormalities associated with compression of the esophagus primarily occur at birth or in the immediate neonatal period. However, as the result of arteriosclerotic vascular disease or aneurysm formation, anomalies which were asymptomatic postnatally may produce dysphagia in the adult. A retrospective analysis of 59 cases with aortic arch anomalies presenting initially in adulthood revealed characteristic clinical signs and symptoms. An aberrant right subclavian artery with left aortic arch was the most frequently encountered abnormality. The embryologic development of each vascular anomaly is described and the value of selective arteriography with contrast esophagography is stressed. Patients with minimal swallowing impairment are treated with dietary management alone. Surgical division of the anomalous artery is indicated only when severe dysphagia is associated with progressive life-threatening anorexia and weight loss.

Adult↗
PubMedDate not supplied

Evaluation of randomized preoperative and postoperative radiation therapy for supraglottic carcinoma. Preliminary report.

One hundred and ten patients with supraglottic squamous cell carcinoma have been randomized for preoperative radiation therapy and surgery versus surgery and postoperative radiation therapy. Data have been analyzed on 94 patients in this preliminary report. The differences between the two groups with respect to local control and survival are not statistically significant at this time. Additional accrual and continued follow-up are necessary in order to make a more definite treatment comparison.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Value of radionucleotide scanning in the staging of head and neck carcinoma.

The presence or absence of distant metastases in squamous cell carcinoma of the head and neck is critical in making rational therapeutic decisions. Radionucleotide bone and liver scans are frequently utilized in the initial evaluation of these patients for possible distant metastases. The true value of routine bone and liver scans in the initial staging of primary squamous cell carcinoma of the head and neck is unknown. One hundred eighteen patients with primary squamous cell carcinoma of the head and neck, evaluated during a five-year period, were retrospectively reviewed. Eight percent were stage I, 18% stage II, 21% stage III, 53% stage IV. Because metastatic carcinoma of the head and neck is primarily regional or pulmonary, the low prevalence of liver and bone metastases limits the usefulness limits the usefulness of these radionucleotide scans. We conclude that routine bone and liver scanning is not a valuable diagnostic technique in the initial staging of head and neck carcinoma when clinical or biochemical evidence of distant metastases is not present.

Adult↗
PubMedDate not supplied

Osteoradionecrosis of the head and neck: a case of a clavicular-tracheal fistula secondary to osteoradionecrosis of the sternoclavicular joint.

Radiation therapy is an integral part of treatment for head and neck cancer, but its use is not without complications. We describe the first reported sternoclavicular-tracheal fistula resulting from osteoradionecrosis (ORN) at the medial clavicle. This ORN resulted from definitive radiation therapy for a primary pyriform sinus squamous cell carcinoma. The diagnosis of ORN was made by fiberoptic bronchoscopy. The physiologic damage of ORN is based on a compromised blood supply and altered metabolism of bone formation secondary to effects of ionizing radiation. Treatment requires meticulous hygiene, antibiotics, and debridement as conservative therapy. Radical surgery and reconstruction may be indicated in refractory cases. A thorough preirradiation assessment of patients is mandatory to decrease the incidence of radiation-induced ORN.

Bone Diseases↗
PubMedDate not supplied

Olivocochlear bundle activity recorded in awake cats.

Multi-unit activity was recorded in awake cats from the crossed olivocochlear bundle (COCB). Miniature stainless stell concentric electrodes were chronically implanted onto the floor of the fourth ventricle of six animals. There was no activity at the electrode tip in anesthetized animals, while in awake cats a great deal of unit activity could be seen. A correlation between COCB activity and ongoing behavioral activity such as scratching, grooming, yawning, or orientation could not be established. It was found, however, that the multi-unit responses in the COCB statistically increased their firing rate during acoustic stimulation, and a 500-Hz tone was found to be most effective. The electrode locations were histologically confirmed. The present results are similar to other data that describe unit activity in the olivocochlear bundle of decerebrate cats. The capacity to record from this fiber tract in awake animals, however, provides a new tool for studying the peripheral efferent pathway of the auditory system.

Acoustic Stimulation↗
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Benign osteoblastoma of the maxillary sinus.

The benign osteoblastoma is an uncommon bone tumor. It is a benign but actively growing neoplasm that must be differentiated from more aggressive bony lesions. A review of the literature indicates that 14% of benign osteoblastomas are located in the head. The clinical, radiologic, and pathologic features and treatment of the benign osteoblastoma are discussed. In addition, the third case of a benign osteoblastoma of the paranasal sinuses, and the first of the maxillary sinus, is described.

Adult↗
PubMedDate not supplied

Mucoepidermoid carcinoma of the hypopharynx.

Mucoepidermoid carcinoma is most commonly found in the parotid gland. It rarely occurs in the larynx and hypopharynx. There are only 32 reported cases from these areas. A case of a mucoepidermoid carcinoma of the hypopharynx is presented. Although the initial impression was squamous cell carcinoma, glandular structures were found in metastatic lymph nodes in the neck specimen, and after mucicarmine stains were positive, the final diagnosis was changed to mucoepidermoid carcinoma. This case illustrates the difficulty in diagnosing mucoepidermoid carcinoma, especially in unexpected locations. Differentiating mucoepidermoid carcinoma from other neoplasms is important because treatment may differ depending on the diagnosis. The pathologic spectrum of mucoepidermoid carcinoma is presented, and the management of these tumors with respect to the histologic grade is discussed.

Carcinoma↗
PubMedDate not supplied

An intraoral self-contained artificial larynx.

It has been estimated that approximately one third to one half of persons undergoing total laryngectomy do not obtain a satisfactory voice. These patients remain aphonic or use artificial larynges to facilitate their communication. A multidisciplinary group at Thomas Jefferson University has developed a miniaturized artificial larynx that fits on a dental prosthesis or dental plate which has over a 100-dB sound pressure level output at the source and is powered by two hearing aid batteries with a life expectancy of over 100 hours of continuous use. Clinical trials have shown that persons using other artificial devices quickly adapt to this new artificial larynx, and the first person who began using the device, an Italian, commented that he could now use both hands; and felt that this was a great help because of his ethnic background.

Dentures↗
PubMedDate not supplied

Hyperosmolar nonketotic coma: prevention, diagnosis, and treatment.

With the multi-faceted approach to head and neck cancer today, maintaining caloric intake by long-term enteral hyperalimentation is commonplace. Along with the tremendous advantages of this form of nutrition, the disadvantage of hyperosmolar nonketotic diabetic acidotic coma is present. Mortality rates are quoted from 40% to 70% according to the literature reviewed. Therefore, prevention is the best form of treatment. The cause, diagnosis, and treatment will be discussed.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Comparison of preoperative and postoperative radiation therapy for patients with carcinoma of the head and neck. Interim report.

Three hundred and fifty-four patients with squamous cell carcinoma of the oral cavity, oropharynx, supraglottic larynx, hypopharynx or maxillary sinus have been randomized for preoperative radiation therapy and surgery versus surgery and postoperative radiation therapy plus, in the case of patients with lesions of the oral cavity and oropharynx, radical radiation therapy. Data have been analyzed on 320 patients in this interim report. In the supraglottic larynx group local-regional control is significantly better for surgery and postoperative radiation therapy. The treatment differences in local-regional control in the oral cavity oropharynx and hypopharynx groups are not statistically significant. No statistically significant treatment differences exist for survival in all sites or in any site; continued follow-up is necessary to make definite treatment comparisons.

Carcinoma, Squamous Cell↗