Biomedical subjects

S D Gray

Publications and source records attributed to S D Gray.

At least 55 records · Page 3Linked to original sources

PubMed1994

Morphologic ultrastructure of anchoring fibers in normal vocal fold basement membrane zone.

Anchoring fibers are collagenous structures that help secure basal cells to the superficial layer of the lamina propria (SLLP). Transmission electron microscopy was used to study the morphology and organization of these anchoring fibers at the human vocal fold basement membrane zone. This study shows that anchoring fibers loop from the lamina densa through the lamina propria and reattach to the lamina densa. Collagen fibers from the lamina propria appear to pass through the loops created by the anchoring fibers. This relationship partially explains how the epidermis secures itself to the SLLP during vibration resulting from phonation. The population density of anchoring fibers and genetics is discussed.

Aged↗

PubMed1994

Development of soleus muscles in SHR: relationship of muscle deficits to rise in blood pressure.

Skeletal muscles from 24- to 28-wk-old spontaneously hypertensive rats (SHR) exhibit decreased contractile capacity and resistance to fatigue. The present study was designed to determine the age at which these deficits first appear and their relationship to the development and progression of the rise in blood pressure. SHR soleus was significantly weaker than age-matched Wistar-Kyoto (WKY) soleus at all ages studied, but resistance to fatigue varied with age. Soleus muscles in 6- to 8-wk-old SHR were, on average, more fatigue resistant than age-matched WKY muscles. Fatigue resistance in 16- to 18-wk-old animals, however, was similar in the two strains. There were no significant differences in soleus growth or fiber type distributions in the strains between 6 and 18 wk of age. WKY soleus in 24- to 28-wk-old animals were hyperpolarized after the fatigue test. SHR fibers, in contrast, did not hyperpolarize after exercise, possibly reflecting an age-related reduction in sarcolemmal Na+ pump number or function. Soleus in younger SHR also provided an indication of a developing membrane dysfunction, since extracellularly recorded M waves showed greater changes in SHR than in age-matched WKY muscles during exercise. The rise of blood pressure in SHR is genetically based, but it is not clear that the genetic defects responsible for hypertension also produce the observed deficits in skeletal muscle function.

Action Potentials↗

PubMed1994

Increased Na(+)-K+ pump number and decreased pump activity in soleus muscles in SHR.

We have previously demonstrated electrophysiological and contractile abnormalities in soleus muscles of the spontaneously hypertensive rat (SHR). The age-related decrease in force and fatigue resistance observed in SHR muscles may be produced by alterations in sarcolemmal ion conductance and/or Na+ pump function. The experiments reported in the present paper were designed to assess the functional capacity of the Na+ pump in 6- to 8- and 24- to 28-wk-old SHR and Wistar-Kyoto (WKY) soleus muscles and to correlate pump activity with Na+ pump number and binding affinity ([3H]ouabain binding). Functional capacity was determined by measuring the change in resting membrane potential (RMP) of soleus muscle fibers in response to agents that stimulate (epinephrine and insulin) or inhibit (ouabain) the pump and by measuring maximum ouabain-suppressible 86Rb+ uptake in Na(+)-loaded muscles. Na+ pump number and affinity were quantified by determining the specific binding of [3H]ouabain in soleus muscle slices. SHR soleus muscles contain a greater number of Na+ pump sites (ouabain binding sites) than are present in age-matched WKY muscles but also experience a significant decrease in pump activity with age. SHR may upregulate pump number in response to the significantly higher intracellular Na+ concentration found in soleus muscles at all the ages examined. The apparent reduction in pump capacity with age may play a major role in the observed age-related decrease in SHR soleus force and fatigue resistance.

Aging↗

PubMed1994

Soleus muscle contractile properties in hypertensive rats.

Three types of hypertensive rats, and their normotensive controls, were assessed to determine the effects of high blood pressure on the contractile and fatigue properties of the soleus muscle. Spontaneously hypertensive rat (SHR) soleus developed less contractile force and fatigued more rapidly than normotensive Wistar-Kyoto (WKY) controls. In contrast, normotensive Wistar and Wistar-1 kidney/1 renal clip hypertensives were similar in their responses, and Dahl salt-sensitive hypertensives and Dahl salt-resistant controls also did not exhibit any significant differences in tension development or endurance. The results suggest that the decreased ability to develop force and maintain it during stimulation may not be directly related to the high blood pressure in SHR. It may instead be related to a gene defect that cosegregates with the loci responsible for the rise in blood pressure. The reduced endurance in SHR may be associated with an increased accumulation of K+ in the muscle during contraction, which decreases performance. It may also decrease the ability of the vessels to dilate during muscle contraction, preventing maintenance of an adequate blood supply.

Animals↗

PubMed1994

Effect of chronic blood pressure reduction on soleus muscle contractile properties in spontaneously hypertensive rats.

Soleus muscle in Wistar-Kyoto rats (WKY), as well as in most normotensive mammals, is highly fatigue resistant. In 6-mo-old spontaneously hypertensive rats (SHR), however, soleus muscle generates less specific force and experiences a more rapid rate of fatigue than in age-matched WKY. The present experiments tested the hypothesis that antihypertensive treatment with hydralazine or amlodipine would shift the contractile force and fatigue resistance profile of SHR soleus toward that which characterizes WKY. Hydralazine was given via the drinking water (100 mg/l) and amlodipine via the food (1 g/4 kg rat chow) to two separate groups of animals, starting at the age of 16 wk. At 24-26 wk of age soleus twitch and tetanic force generation and the rate of fatigue were evaluated during a 4-min period of repetitive stimulation. Although both hydralazine and amlodipine lowered blood pressure, they had different effects on muscle function. Hydralazine decreased force generation in both WKY and SHR at all stimulation frequencies; it did not change the fatigue properties of SHR but made WKY soleus less fatigue resistant. Amlodipine, on the other hand, increased contractile force in both WKY and SHR and increased fatigue resistance in SHR. Amlodipine is a dihydropyridine that blocks L-type channels, thereby preventing entry of Ca2+ into the muscle. We suggest that Ca2+ entry during activity stimulates Ca-activated K+ efflux in SHR and adds to the extracellular load of K+. Increased extracellular K+ can in turn depress contractile performance.

Amlodipine↗

PubMed1994

Fundamental frequency and amplitude perturbation in reconstructed canine vocal folds.

A submucosal fat autograft was implanted within the cover of injured vocal folds of 5 dogs. The implant occurred 6 weeks after unilateral mucosal excision had been performed. Three months postoperatively the larynges of these animals were excised and their phonation was compared to that of normal dog larynges and to other larynges with mucosal excision (but without fat grafting). Radiated acoustic pressure from the artificially driven larynges was recorded and digitized at 20 kHz with 16-bit resolution. Amplitude and fundamental frequency perturbations were extracted from a segment of phonation to assess the stability of the acoustic signals from the 3 groups. It was found that fat augmentation after mucosal excision reduced amplitude and frequency perturbation measures. There was no significant difference between fat-augmented and normal vocal folds. The acoustic measures were also positively correlated with phonation threshold and phonation efficiency measures reported earlier. The results suggest that submucosal fat autograft implantation within an injured vocal fold cover can restore not only the "ease" of phonation, but also the stability of phonation, which is a component of vocal quality.

Adipose Tissue↗

PubMed1994

Arytenoid separation for impaired pediatric vocal fold mobility.

Impaired vocal fold motion may result from cricoarytenoid joint fixation, bilateral vocal fold paralysis, or interarytenoid scarring. Traditional surgical techniques have focused on lateralization or resection of the arytenoid for airway improvement. This paper discusses 3 cases of bilateral reduced vocal fold motion of neurogenic cause treated with posterior cricoid grafting to cause a wider resting position of the vocal folds and arytenoids. Airway improvement occurred in all. The voice results have been encouraging. Advantages of this procedure are that the vocal folds are symmetric, there is no vocal fold or joint scarring, and the larynx remains a candidate for electrical pacing when that becomes available. Acoustic and aerodynamic voice results are presented. The results should be considered preliminary.

Arytenoid Cartilage↗

PubMed1994

Head and neck malformations of the pediatric airway.

The authors describe the head and neck malformations that can affect the upper aerodigestive tract. The article is organized so that it begins with the nose and extends through the larynx. A diagnostic table for the localization for an airway lesion is given. Medical and surgical treatment regarding various malformations including choanal atresia, Pierre Robin sequence, laryngomalacia, laryngeal edema, and subglottic stenosis are discussed.

Airway Obstruction↗

PubMed1993

Human papillomavirus infection in papillomas and nondiseased respiratory sites of patients with recurrent respiratory papillomatosis using the polymerase chain reaction.

We examined human papillomavirus (HPV) infection in biopsy specimens and cellular scrapes that were taken from respiratory papillomas and six nondiseased sites from the respiratory tract of seven patients. Human papillomavirus was detected by polymerase chain reaction amplification, followed by DNA hybridization with probes for specific HPV types. All papillomas (100.0%, n = 5) were positive only for HPV type 6 or 11. In the nondiseased site specimens, 61.3% (19/31) of the specimens were positive, again only for HPV type 6 or 11. Among the nondiseased site specimens from the cervical trachea, intrathoracic trachea, and bronchus, 80% to 100% were HPV positive compared with only 25% to 50% of HPV infection detected in the nasopharynx, posterior tonsillar pillar, and aryepiglottic fold. These results support the tenet that HPV infection is present in clinically normal respiratory tract tissue and that the reservoir site of reinfection is more commonly in the lower airway. However, patients with upper-airway involvement were more likely to be diagnosed as having severe disease.

Adult↗

PubMed1992

Appearance of alpha 1-adrenergic receptors in soleus muscles from SHR.

The depressed functional capabilities of spontaneously hypertensive rat (SHR) muscles, reported previously (Exp. Neurol. 95: 249-264, 1987), may reflect a decrease in muscle responsiveness to catecholamines occurring as a consequence of exposure to the elevated level of plasma catecholamines in SHR. Responsiveness to applied catecholamines was determined in SHR and Wistar-Kyoto rat (WKY) soleus by measuring muscle resting membrane potentials (RMP) in vitro. Epinephrine (10(-6) M) produced a similar membrane hyperpolarization in SHR and WKY fibers. Pretreatment with the beta-antagonist propranolol completely blocked the epinephrine-induced hyperpolarization in WKY, but not in SHR. SHR soleii from both young and old rats contained a population of alpha 1-adrenergic receptors also associated with membrane hyperpolarization. The alpha-receptors appeared to be associated with a ligand-gated Ca(2+)-influx pathway, since the alpha-agonist-induced membrane hyperpolarization required the presence of Ca2+ in the extracellular medium. The alpha-induced hyperpolarization was also blocked by apamin, a derivative of bee venom which blocks a Ca(2+)-activated K(+)-efflux pathway in a variety of tissues. The possible role of these novel alpha-receptors in skeletal muscle function, and their relationship to the development of hypertension, is uncertain.

Aging↗

PubMed1992

Detection of human papillomavirus infection in diseased and nondiseased sites of the respiratory tract in recurrent respiratory papillomatosis patients by DNA hybridization.

We examined 12 recurrent respiratory papillomatosis patients, who were undergoing treatment for recurrence of their disease, for the presence of human papillomavirus (HPV). Biopsies were obtained from their respiratory papillomas and nondiseased sites (NDS) of the respiratory tract: the nasopharynx, posterior tonsillar pillar, aryepiglottic fold, cervical trachea, intrathoracic trachea, and bronchi. The presence of HPV DNA was determined by using the ViraPap/ViraType DNA hybridization procedure. Two thirds of the patients were infected with HPV 6/11 in either the diseased papilloma or NDS: 50% of patients with papilloma specimens typed positive (6 of 12), and 40% of the patients typed HPV-positive in one or more biopsies from the NDS (4 of 10). No single NDS was more likely to be infected with HPV than any other. No oncogenic HPV types 16/18 or 31/33/35 were detected in the papillomas or NDS of these patients. Only patients with multiple, and not isolated, papilloma involvement were found to harbor HPV DNA in NDS; and 80% of those with infected NDS, compared to 20% of those without infected NDS, required a shorter (no more than 3 months) surgical treatment interval. Our results show that HPV infection frequently persists in adjacent, clinically normal sites, and suggest that the extent of NDS involvement may predict both the extent of disease and the likelihood of recurrence.

Adolescent↗

PubMed1992

Vocal evaluation of thyroplastic surgery in the treatment of unilateral vocal fold paralysis.

Vocal function was assessed in 15 patients who received thyroplasty type I for the rehabilitation of unilateral vocal fold paralysis. The function was assessed by perceptual evaluation, voice intensity and frequency range profiles, and questionnaire. Goals of the study were to evaluate the efficacy of thyroplasty in improving the voice, to compare postoperative thyroplasty voices to normal voices, and to correlate objective measurements to the results of the questionnaire regarding satisfaction with the voice. Perceptual evaluations were performed by randomizing normal and thyroplasty voices on a recording tape. The voices on the tape were then rated by independent, blinded, trained listeners. The perceptual qualities of pitch, intonation, and loudness were not statistically different than normals; however, voice qualities of strain, breathiness, hoarseness, harshness, and unsteadiness were different than normals. Mean frequency range and mean intensity range were moderately to severely reduced from normals with a wide variation being present in the results. The correlation between the higher threshold phonation pressures and decreased intensity ranges found in some patients is discussed. Questionnaire results indicated that a high degree of satisfaction with the surgery was present (92%). Extreme or general satisfaction with voice was present in 73%. The most difficult voicing was experienced at work, with 25% needing to adjust their employment to accommodate their voice abilities. These results indicate that thyroplasty type I is effective in partially rehabilitating unilateral voice fold paralysis. Voice function is still not normal, probably in part due to the underlying disease.

Adolescent↗

PubMed1992

Results of multidisciplinary management of bilateral cleft lip and palate at the Iowa Cleft Palate Center.

Bilateral cleft of the lip and palate is by many standards the most complex and severe form of the defect. The complexity and severity of the defect require an unusual degree of cooperation among all specialists and especially between the surgeon and the orthodontist. There are no published findings that we know about in which comprehensive data from a number of disciplines are reported for the same group of bilateral cleft patients. Fifty randomly selected patients with bilateral complete clefts were examined by the Iowa team and two orthodontists from other institutions. The evaluations revealed that a large number of patients over the age of 10 have multiple residual problems requiring further treatment. Only 23 percent of the older patients studied were judged to have had treatment completed by the surgeon, speech pathologist, and orthodontist. It is very difficult to state whether the results obtained by our team can be considered satisfactory because there are no comparable studies that have attempted to evaluate the same parameters in multidisciplinary management.

Adolescent↗

PubMed1991

Cricoid quartersection vs. anterior-posterior cricoid split: effect on subglottic growth in rabbits.

Five-week-old New Zealand white rabbits were divided into three groups: control, anterior-posterior cricoid split with stent, and cricoid quartersection (anterior-posterior-lateral cricoid split) with stent. The stents were removed 2 weeks after placement. The rabbits were allowed to grow for six months, at which time they were killed and the larynges were studied. Average, minimal, and maximal subglottal cross-sectional areas were calculated for each animal and adjusted for weight. The cricoid quartersection group had significantly greater average, minimal, and maximal subglottal cross-sectional areas compared to controls and significantly greater minimal and maximal cross-sectional areas compared to the anterior-posterior cricoid split group. The anterior-posterior cricoid split group and the control group did not significantly differ with respect to any of the three parameters. The results indicate that anterior-posterior cricoid split and cricoid quartersection do not adversely affect subglottic growth. Cricoid quartersectioning was superior to the anterior-posterior cricoid split in its ability to expand subglottic airway dimension.

Animals↗

PubMed1991

Apparent upregulation of Na+,K+ pump sites in SHR skeletal muscle with reduced transport capacity.

Slow-twitch, oxidative skeletal muscles in SHR exhibit several physiological defects, including a reduced ability to maintain force during high frequency repetitive stimulation (1). Muscle fatigue may be produced by one of a variety of factors acting at different levels of the neuromuscular system. Several lines of evidence, however, suggest that SHR soleus fatigues more rapidly than WKY soleus because SHR muscles allow more K+ to accumulate in the extracellular space during repetitive muscle activity. An increase in extracellular K+ can lead to a failure in the generation or conduction of muscle action potentials. Comparison of the compound action potentials recorded from SHR and WKY muscles during repetitive stimulation provided evidence for a decrease in excitability of SHR soleus. Since the K+ released from muscle fibers during exercise is returned to the fiber principally via the activity of the Na+, K+ pump, the increase in extracellular K+ in SHR muscle may reflect a decrease in pump capacity. Measurements including intracellular K+ and Na+ content at rest, the level of hyperpolarization produced by the addition of epinephrine and insulin to SHR soleus and the post-exercise recovery of resting membrane potentials all appear to indicate that Na+, K+ pump capacity is reduced in SHR soleus muscles. Nonetheless, ouabain binding studies show a significantly greater number of pump sites in SHR muscles. The data suggest that Na+ pump activity is decreased in SHR soleus muscles without an apparent reduction in either the number of pump sites or in pump binding affinity.

Animals↗

PubMed1991

Reciprocal embryo transfer between SHR and WKY. II. Effect on cardiovascular development.

In order to study the in vivo effect of putative hypertensinogenic factors on early development of the cardiovascular system, embryos were reciprocally transferred between WKY and SHR to allow embryonic and fetal development of WKY in a hypertensive intrauterine environment and SHR in a non-hypertensive uterine environment. In one day-old neonates blood vessel dimensions and blood pressures were assessed. Pressures were also measured in animals which matured to the adult stage to determine whether there were any long-term effects on pressure of having developed in an in utero environment different from the one they would have naturally experienced. The data indicate that there are no consistent effects of intrauterine environment on vascular development, as indicated by the fact that normalized wall/lumen ratios were not different between normal and transferred animals, and immediate and long-term pressures were also similar in normal and transferred groups.

Animals↗

PubMed1991

Sports strapping and bandaging.

Strapping with adhesive tape plays a significant part in the prevention of joint injuries, particularly at the ankle and hand, and is important during early management of injury and rehabilitation. Recurrence of injury when the athlete recommences training is less likely with supportive strapping.

Athletic Injuries↗

PubMed1989

Beta-receptor properties in soleus muscles from spontaneously hypertensive rats.

We have compared the properties of beta-adrenergic receptors in slow-twitch, oxidative skeletal muscles (soleus) from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats at three different ages. The investigation was based on the hypothesis that the increase in Na+ content and decrease in fatigue resistance observed previously in the soleus of SHR might be the result of a down regulation of muscle beta-receptors. Activation of beta-adrenergic receptors in skeletal muscle stimulates sarcolemmal sodium-potassium adenosine triphosphatase, which produces an efflux of Na+ and an influx of K+. Receptor down-regulation would be expected to reduce hormonal stimulation of Na+ pump activity, particularly during exercise. The results of receptor binding studies, however, and an investigation of cyclic adenosine monophosphate (cAMP) production in response to applied epinephrine indicated that there were no significant differences in receptor properties in the soleus muscles of SHR and WKY rats. Receptor number and affinity were the same in the two strains, and the rate, magnitude, and duration of the increase in cAMP in response to 10(-6) M epinephrine were also similar. beta-Adrenergic receptor down-regulation does not appear to be a generalized phenomenon in tissues of SHR, despite the appearance of other physiological changes in the tissue.

Animals↗