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D S Parsons

Publications and source records attributed to D S Parsons.

At least 55 records · Page 3Linked to original sources
PubMed1992

Hippocampal phosphoinositide turnover is altered by hippocampal sympathetic ingrowth and cholinergic denervation.

Cholinergic denervation of the hippocampus, by medial septal (MS) lesions, results in an unusual neuronal rearrangement in which peripheral sympathetic nerves, which originate from the superior cervical ganglia, grow into the hippocampal formation. To assess the functional significance of hippocampal sympathetic ingrowth (HSI), hydrolysis of phosphoinositides was examined in three groups: control, MS lesions + sham ganglionectomy (HSI group); and MS lesions + ganglionectomy (MSGx; no ingrowth). Four months after surgery, both norepinephrine (NE) and carbachol were found to produce a dose-dependent increase in the hydrolysis of hippocampal phosphoinositides in all groups. However, the presence of HSI, when compared to control and MSGx groups, significantly enhanced the turnover of phosphoinositides when stimulated by carbachol, but not NE. In further studies, the time course of this effect was studied. One week after surgery, carbachol-stimulated phosphoinositide turnover was equivalent among all groups; by 2 weeks, phosphoinositide turnover was enhanced in the HSI and MSGx group; by 4 weeks, PI turnover was markedly diminished in the MSGx group when compared to both the HSI and control groups, which were equivalent to each other. To ensure that the ganglionectomy alone did not alter phosphoinositide turnover, a ganglionectomy-alone group was studied at the 4-week time point. In this group, phosphoinositide turnover was equivalent to controls, suggesting no influence of the superior cervical ganglia on this response. In all groups, atropine inhibited carbachol-stimulated phosphoinositide turnover. These results suggest that both cholinergic denervation (i.e., MSGx group) and HSI produce marked functional alterations in hippocampal metabolic activity.

Animals↗
PubMed1992

Treatment of chronic erosions of junctional epidermolysis bullosa with human epidermal allografts.

We have successfully treated chronic central facial erosions of a patient with junctional epidermolysis bullosa using cultured epidermal allografts. Keratinocytes isolated from a skin biopsy of the patient's biological mother were used to generate the epidermal allografts. Significant re-epithelialization occurred during the course of four grafting procedures. Cultured epidermal allografts appear to be a promising method for treatment of chronic erosions of junctional epidermolysis bullosa.

Cells, Cultured↗
PubMed1992

Pediatric tracheobronchomalacia and major airway collapse.

Based on histopathologic, endoscopic, and clinical findings of the flaccid airway, new descriptive terms--major airway collapse types 1 through 3--are proposed to better define tracheobronchomalacia. A typing and grading system is offered to objectively analyze and compare clinical cases. Endoscopic and anesthetic techniques are presented for use in children with respiratory distress suggestive of tracheobronchomalacia. Spontaneous ventilation with laryngoscopic insufflation of anesthetic gases and the use of small-diameter telescopes without bronchoscopes are key elements for the examination of the dynamic pediatric airway. Pitfalls of classic bronchoscopy techniques are described that can lead to a missed diagnosis. Between 1987 and 1990, over 200 telescopic bronchoscopies were performed at Wilford Hall US Air Force Medical Center on 129 children 3 years old and younger with respiratory distress. By means of the described techniques, 38 children (30%) with major airway collapse were identified. Major airway collapse was associated with a variety of endoscopic and cardiac abnormalities. With the emergence of sophisticated neonatal pediatric respiratory care, a growing number of premature infants with major airway collapse are surviving. Early, precise endoscopic diagnosis allows optimal management.

Abnormalities, Multiple↗
PubMed1991

The two-headed stethoscope: its use for ruling out airway foreign bodies.

Foreign body aspiration is a common concern for physicians and surgeons who care for children. Evaluating infants and toddlers to rule out this possible diagnosis is often fraught with difficulties. Specifically, the standard stethoscope is of limited use unless unilateral asymmetry of breath sounds can be appreciated. Inspiratory and expiratory chest X-rays in children often appear to show a very similar diaphragmatic excursion and, unless the object is radiodense, the determination of foreign body aspiration is frequently not possible. Other procedures, such as flexible or rigid endoscopy, are more invasive and are reserved for children with positive findings or a less acute but more perplexing scenario. We present the use of the two-headed stethoscope as an option for evaluation of children to rule out foreign body aspiration. Our experience with this instrument over the past 10 years has consistently allowed us to non-invasively differentiate the presence or absence of objects in the airway.

Airway Obstruction↗
PubMed1991

Volunteer otolaryngology practice in rural Mexico.

Medical missions, particularly with religious or military affiliation, are becoming more commonly performed in the Third World. Modern surgical techniques for correcting congenital anomalies frequently require staged operative procedures with long-term follow-up. However, in remote or isolated Third World villages, operative procedures must often be done at a single setting, without staging, utilizing limited intraoperative equipment. Very short postoperative hospitalizations may be all that are available and follow-ups are severely limited. We report our experience on a two-week mission to Mexico where 46 major otolaryngologic surgeries were performed. Follow-up was limited, in most patients, to visits within only a few days of the surgical procedure. Techniques for Third World otolaryngologic surgical experience are discussed including the correction of cleft deformities.

Humans↗
PubMed1991

Paranasal sinus bony anatomic variations and mucosal abnormalities: CT analysis for endoscopic sinus surgery.

Coronal plane computerized tomographic (CT) scanning has dramatically improved the imaging of paranasal sinus anatomy as compared to sinus radiographs. Increasingly, subtle bony anatomic variations and mucosal abnormalities of this region are being detected. Data regarding the "background" prevalence of these findings are needed to determine their clinical relevance. A detailed analysis of coronal plane CT scans of the paranasal sinuses obtained in 202 consecutively imaged patients was conducted. Special attention was directed toward identifying bony anatomic variations and mucosal abnormalities. Anatomic variations studied included pneumatization of the middle turbinate, paradoxical curvature of the middle turbinate, Haller's cells, and pneumatization of the uncinate process. Such bony anatomic variations were detected in 131 (64.9%) of 202 patients and were found with a similar frequency in patients scanned for sinus complaints and in those scanned for nonsinus reasons. Mucosal abnormalities were detected in 168 (83.2%) of 202 patients. For those patients scanned during the evaluation of sinus-like complaints, mucosal abnormalities were noted in 153 (92.2%) of 166 cases, and were predominantly detected in the anterior ethmoid region. For patients scanned during nonsinus evaluations, mucosal abnormalities were detected in 15 (41.7%) of 36 cases, without predilection for the anterior ethmoid region. Discussion regarding the prevalence and clinical significance of paranasal sinus bony anatomic variations and mucosal abnormalities is included as a guide to assist the otolaryngologist and/or radiologist in the evaluation of coronal sinus CT scans.

Adult↗
PubMed1991

Comparison of expandable endotracheal stents in the treatment of surgically induced piglet tracheomalacia.

Present surgical alternatives for pediatric tracheobronchomalacia are limited and associated with many potentially undesirable complications. The feasibility of different intraluminal expandable endotracheal stents for the treatment of surgically induced tracheomalacia was analyzed in 27 piglets. A potentially fatal tracheomalacia was surgically created. Either a stainless steel "zig-zag" stent or a woven polymeric stent was then implanted. Tracheal patency, mucosal function, histopathologic respiratory tract changes, and effects of the stent on esophageal motility were evaluated over a 16-week period. Piglets with steel stents uniformly experienced intense inflammation leading to tracheal dysfunction and death. Piglets with polymeric stents experienced minimal respiratory symptoms. Expandable polymeric endotracheal stents alleviate surgically induced piglet tracheomalacia, were easy to insert, allowed for tracheal growth, and reduced the need for high-risk surgical procedures with prolonged ventilatory support.

Animals↗
PubMed1991

Interaction of neurotransmitter systems in the hippocampus: a study of some behavioral effects of hippocampal sympathetic ingrowth.

Recent research has suggested that normal learning/memory may depend upon the balance between central noradrenergic and cholinergic systems. This hypothesis has particular relevance to the study of the neuronal rearrangement that follows cholinergic denervation of hippocampus. In this, peripheral noradrenergic fibers, originating from the superior cervical ganglion, grow into the hippocampus in response to lesions of the medial septal (MS) cholinergic cell bodies. To understand further the influence of hippocampal sympathetic ingrowth (HSI) on behavior, gustatory neophobia, passive avoidance (PA) learning, and open field activity were studied. Male Sprague-Dawley rats underwent one of four surgical procedures: MS lesions and sham ganglionectomy (ingrowth group; MS/HSI group), sham MS lesions and ganglionectomy (Gx group), MS lesions and ganglionectomy (no-ingrowth group; MS/Gx group), or sham MS lesions and sham ganglionectomy (CON group). Behavioral testing began 4 weeks following surgery. The time to acquire the PA task was similar among all groups; however, the initial latency to enter the dark chamber of the PA apparatus was longer, and the number of partial reentries greatest, for MS/HSI animals. Retention testing at 24 hr revealed that MS/HSI animals were significantly impaired when compared to the CON and MS/Gx groups. The MS/Gx and the CON groups demonstrated gustatory neophobia, preferring water to saccharin solution, while gustatory neophobia was absent in the MS/HSI and Gx groups. MS/HSI animals were found to be more active in the open field than the other groups. Biochemical studies revealed the expected loss of ChAT activity in the dorsal and ventral hippocampi of lesioned animals along with elevated levels of norepinephrine (NE) in the dorsal hippocampus of MS/HSI animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Treatment of severe bronchomalacia with expanding endobronchial stents.

Respiratory compromise from tracheobronchomalacia in children varies from mild to severe, but can result in either reflex apnea or death. Such severe cases may be unresponsive to aggressive medical management, and surgical options must be considered. Current surgical alternatives are limited and are associated with many potentially undesirable complications. Failure rates are often high. We present two infants with profound life-threatening airway malacia treated by endoscopic placement of a self-expanding endobronchial stent. A description of their anomaly, surgical management, and long-term care is included. The expandable stent may obviate the need for complex high-risk surgical procedures and prolonged ventilatory support.

Airway Obstruction↗
PubMed1990

Tracheal reconstruction with polytetrafluoroethylene graft in dogs.

Use of prosthetic materials for long-segment tracheal reconstruction has been limited owing to infection, graft migration, ingrowth of fibrous tissue, and stenosis. Polytetrafluoroethylene (PTFE) is flexible and porous, and it may resist infection more than previously used materials. We evaluated PTFE for use in long-segment tracheal reconstruction. A 5-cm segment of trachea was resected in 9 dogs and replaced with a 20-mm reinforced PTFE graft using 4-0 Vicryl sutures. In 2 control dogs, one tracheal arch was resected and a primary anastomosis was performed. The animals were followed up with weekly bronchoscopy and endoscopic photography. Euthanasia was performed at 16 weeks or when signs of respiratory distress developed. At postmorten examination, the anastomoses were examined grossly and with light and scanning electron microscopy. In all 9 dogs that underwent tracheal replacement with PTFE, granulation tissue developed at the anastomoses resulting in airway obstruction after 3 to 8 weeks. No epithelial growth occurred over the graft between the anastomoses. The control animals did well. We conclude that granulation tissue formation at the anastomosis and the lack of respiratory epithelial ingrowth across the graft makes PTFE unsuitable for long-segment tracheal reconstruction.

Airway Obstruction↗
PubMed1990

The effect of gonadal steroids on the behavioral and biochemical effects of hippocampal sympathetic ingrowth.

Following cholinergic denervation of the hippocampal formation, via medial septal lesions, sympathetic fibers, originating from the superior cervical ganglia, grow into the hippocampus. Previous studies have demonstrated a detrimental effect of these fibers on recovery of a spatial-learning task in male but not female animals. In this study we assessed the role of circulating male sex hormones on the behavioral and biochemical effects of hippocampal sympathetic ingrowth (HSI). For the behavioral studies male Sprague-Dawley rats underwent either sham gonadectomy or gonadectomy and were taught a standard radial 8-arm maze task. Following attainment of criterion animals underwent one of three surgical procedures: sham surgery, MS lesions, MS lesions + ganglionectomy. MS lesions, regardless of the presence of HSI, were found to severely impair reacquisition of the task in both sham-gonadectomized and gonadectomized animals. As expected, in the sham-gonadectomized group, MSGx animals reacquired the task faster than the MS group. However, gonadectomy was found to block the detrimental effect of HSI on behavior. For the biochemical studies hippocampal norepinephrine (NE) and choline acetyltransferase (ChAT) were measured eight weeks after surgery in sham-gonadectomized and gonadectomized animals. MS lesions were found to significantly reduce the ChAT activity, regardless of circulating sex hormones. Gonadectomy was found to significantly reduce the level of NE associated with HSI, while having no effect on central NE in CON or MSGx animals. These studies suggest that circulating male sex hormones can influence both the behavioral and biochemical processes associated with HSI.

Acetylcholinesterase↗
PubMed1990

Adrenoreceptor antagonist treatment influences recovery of learning following medial septal lesions and hippocampal sympathetic ingrowth.

Previous studies have demonstrated that in male rats hippocampal sympathetic ingrowth (HSI), which is induced by medial septal lesions (MS), is detrimental to recovery of spatial learning. The present study was performed in an attempt to determine if this effect was mediated through adrenergic receptor activity. Adult male Sprague-Dawley rats underwent training on a modified version (i.e., 4 arms baited) of a radial-8-arm maze task. Following attainment of learning criterion animals underwent one of three surgical procedures: CON (sham surgeries); MSGx (MS + superior cervical ganglionectomy--to prevent HSI); MS (MS + sham ganglionectomy). Reacquisition trials were performed in the same manner as initial acquisition except animals were treated with vehicle, propranolol (20 mg/kg), or phentolamine (20 mg/kg) 30 minutes prior to testing. As expected, vehicle-treated MS animals took longer to reacquire the task than MSGx animals, who were in turn more impaired than CON animals. Propranolol (beta-adrenergic antagonist) treatment impaired performance of both the MS and MSGx group, but did not alter the CON group. Phentolamine (alpha-adrenergic antagonist) increased the number of trials to reattain criterion in the CON group, had no effect in the MSGx group, and markedly improved performance in the MS group. The results suggest that HSI mediates its detrimental effects through alpha-receptors, while beta-blockade, in the setting of brain injury, is detrimental to performance regardless of the presence or absence of HSI.

Animals↗
PubMed1990

Upper airway obstruction due to massive gingival hyperplasia. A case report and description of a new surgical treatment.

Drug-induced gingival hyperplasia is a frequent complication of phenytoin anticonvulsant therapy. In severe cases, gingival hyperplasia can cause marked cosmetic deformity, phonatory abnormalities and significant occlusal changes which severely restrict masticatory function. Airway obstruction has not been previously reported with this condition. We describe a unique case of massive phenytoin-induced gingival overgrowth causing glossoptosis and subsequent upper airway obstruction. Possible medical and surgical treatment options, including laser wedge resection of the base of the tongue, are discussed.

Airway Obstruction↗
PubMed1990

New set of pediatric laryngoscopes.

With new advances in pediatric otolaryngology, the awareness of difficulties with existing laryngoscope instruments has become more apparent. The following paper introduces four new pediatric laryngoscopes for use in premature infants, the neonate and infant, the toddler-size child, and the preadolescent-size child. The reasons for the need of new laryngoscopes are explained, and the modifications to existing scopes that are currently employed are discussed. The need for continuous insufflation of oxygen during difficult as well as routine intubation is underscored with reference to the current anesthesia literature. Ventilating techniques in laryngoscopy for the non-respirator-dependent child are discussed.

Adolescent↗
PubMed1990

Preoperative hemostatic assessment of the adenotonsillectomy patient.

Intraoperative or postoperative hemorrhage in the patient who has undergone an adenotonsillectomy because of an unrecognized hemostatic defect may increase morbidity and can be potentially life-threatening to the patient in what should be a "routine" procedure. Preoperative identification of occult hemostatic abnormalities, coupled with perioperative management directed at correcting the effects of the defects, should serve to reduce the incidence of this distressful complication. Routine use of preoperative laboratory screening tests for this purpose has been discouraged recently as a result of concerns over cost-effectiveness and the low predictiveness of the tests for bleeding. Our experience with the routine use of a comprehensive hemostatic laboratory screening panel--which includes a bleeding time test--in the adenotonsillectomy patient population demonstrated that 11.5% of our patients had abnormal initial screening laboratory tests; these results were ultimately attributable to occult hemostatic defects. Clinical history, the universally recommended method of preoperative hemostatic assessment, failed to detect any previously unrecognized coagulation disorder. Laboratory screening improved preoperative detection of occult hemostatic defects and allowed for appropriate alterations in perioperative care. Our results with this approach are presented, along with illustrative case histories and a discussion of the current recommendations for preoperative laboratory screening of the hemostatic system, as found in a review of the literature.

Adenoidectomy↗
PubMed1990

Maxillary sinus hypoplasia: classification and description of associated uncinate process hypoplasia.

Maxillary sinus hypoplasia is an anomaly of the paranasal sinuses occasionally encountered by otolaryngologists. Although this entity has been previously reported, an association between maxillary sinus hypoplasia and anomalies of other paranasal sinus structures, such as the uncinate process, has not yet been described. Additionally, the literature lacks a system by which the various types of maxillary sinus hypoplasia can be classified using computerized tomographic (CT) imaging. Two hundred and two consecutive coronal sinus computerized tomographic scans from patients undergoing evaluation at our institution were analyzed to determine the prevalence of MSH and associated paranasal sinus anomalies. The overall prevalence of maxillary sinus hypoplasia was 10.4%. Three distinct patterns of hypoplasia were evident. Type I, characterized by a normal uncinate process, a well-defined infundibular passage, and mild sinus hypoplasia, occurred in 14 patients (6.9%). Type II, characterized by absence or hypoplasia of the uncinate process, an ill-defined infundibular passage, and soft-tissue density opacification of a significantly hypoplastic sinus occurred in 6 patients (3.0%). Type III, characterized by absence of the uncinate process and a profoundly hypoplastic, cleft-like sinus, occurred in 1 patient (0.5%). Recognition of associated anomalies of the uncinate process in patients with maxillary sinus hypoplasia undergoing sinus surgery is of utmost clinical significance because the uncinate process serves as a key landmark during functional endoscopic sinus surgery. Failure to recognize hypoplasia or absence of the uncinate process could lead to inadvertent intraoperative damage to the adjacent medial orbital wall.

Abnormalities, Multiple↗