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Biomedical subjects

A Oliven

Publications and source records attributed to A Oliven.

At least 55 records · Page 3Linked to original sources
PubMed1996

Improved upper airway patency elicited by electrical stimulation of the hypoglossus nerves.

The present study evaluated the mechanisms by which upper airway (UAW)-dilating muscle contraction, elicited by hypoglossus nerve (HGN) stimulation, improved UAW patency. Pressure-flow (P-V) relationships of the isolated UAW as well as the negative intraluminal pressures required to cause UAW collapse were assessed before and during electrical stimulation of the HGN in 8 anesthetized, ventilated dogs. Sectioning of the HGN shifted the P-V relationship to the left, while electrical stimulation resulted in a substantial shift of the curve to the right, indicating UAW dilatation. UAW resistance decreased from 9.0 +/- 1.5 to 0.3 +/- 0.1 cm H2O.1(-1).s during HGn stimulation (p < 0.01). The magnitude of negative intraluminal pressure at which UAW collapse occurred (the critical pressure) increased from -2.7 +/- 0.7 to -13.2 +/- 2.1 cm H2O (p < 0.002). The increase in UAW conductance and stability raised the maximal flow which could be sustained without collapse from 0.28 +/- 0.07 to 2.07 +/- 0.35 l/s during HGN stimulation (p < 0.001). These findings indicate that in the anesthetized dog, UAW muscle contraction improves UAW patency both by dilating the UAW and by stiffening its walls.

Airway Resistance↗
PubMed1995

Dependency of upper airway patency on head position: the effect of muscle contraction.

In the present study we examined the effect of flexion and extension of the head on upper airway (UAW) patency in anesthetized dogs, and compared the dilatory and stabilizing effects of electrically stimulated UAW muscles at the different head positions. Flexion of the head increased UAW resistance (Ruaw) and reduced maximal flow (Vmax), but had little effect on the negative pressure at which UAW collapse occurred (Pcrit). Extension of the head, on the other hand, resulted in more negative Pcrit values and increased Vmax without significantly affecting Ruaw. Electrically induced UAW muscle contraction affected the pressure-flow curve and Ruaw, as well as Pcrit. Changing head position had a substantial effect on the dilatory and stabilizing effect of the various UAW muscles. However, independent of head position, genioglossus stimulation was most effective in reducing Ruaw and increasing Pcrit. We conclude that in the anesthetized, supine dog, head position affects the mechanical properties of the UAW and the effects of UAW muscle contraction.

Airway Resistance↗
PubMed1995

Cutaneous eruption in a patient with cardiac myxoma.

Atrial myxoma was diagnosed in a young woman who had cutaneous and constitutional manifestations clinically suggestive of cutaneous vasculitis without cardiac signs or symptoms. Scrupulous physical and laboratory examinations excluded additional medical disorders. The patient was totally cured by surgical removal of the tumor. Various aspects of the association of cardiac myxoma with dermatological findings are discussed, emphasizing the importance of echocardiography in the diagnostic workup of various skin abnormalities, including unexplained vasculitis, even in the absence of cardiac findings.

Adult↗
PubMed1995

Dilatory effects of upper airway muscle contraction induced by electrical stimulation in awake humans.

During sleep, diminished activity of upper airway dilator muscles (UADMs) is believed to increase upper airway (UAW) resistance and ultimately cause collapse of the UAW. In anesthetized dogs, electrically induced UADM contraction reduces UAW resistance and collapsibility. In this study, we measured the effects of electrically induced contraction of UADMs on pharyngeal resistance (Rph) in seven awake healthy subjects. UAW partial occlusion was achieved by applying external pressure to the submental hyoid region, leading to increased Rph. Transmucosal electrical stimulation (ES) of the base of the tongue was used to preferentially stimulate the genioglossus muscle. Transcutaneous ES using submental and paralaryngeal electrodes were used to preferentially stimulate the geniohyoid and the sternohyoid and sternothyroid muscles, respectively. During the unobstructed state, Rph averaged 6.11 +/- 0.48 cmH2O.l-1.s, and ES produced minimal resistance changes for all stimulation sites tested. In contrast, during the application of external pressure, when Rph was raised to an average of 190 +/- 14% of the baseline value, sublingual ES reduced resistance from 11.67 +/- 1.90 to 6.77 +/- 1.30 cmH2O.l-1.s (P < 0.01). ES at the other sites during the raised Rph state produced only minor statistically insignificant changes in Rph, even when combined submental and paralaryngeal ES was applied. Likewise, only sublingual ES produced measurable anterior movement of the tongue. We conclude that when Rph is raised by exogenous means, sublingual transmucosal ES effectively reduces Rph in awake humans.

Adult↗
PubMed1995

The acoustic properties of snores.

This study was undertaken in an attempt to characterize the acoustic properties of snoring sounds in the time and frequency domains, and to correlate between these properties and the mechanical events underlying their production. Three experimental set-ups were used: 1) Dog model--six mongrel dogs, in which partial upper airway obstruction was created by an implanted supraglottic balloon. Flow, supraglottic pressure, and snoring sounds were recorded during different degrees of obstruction. Fifteen to 20 snores from each dog (total 100 snores) were analysed. 2) Simulated human snores--Six simulated snores from each of four subjects were recorded in two locations (trachea and ambient) with simultaneous airflow, and their correlations examined. 3) Snoring patients--snores were recorded with an ambient microphone from nine subjects with "heavy" snoring and no obstructive sleep apnoea (OSA). Forty to 50 snores from each subject were analysed (total of 400 snores). The snoring sound was analysed in the time (time-expanded waveform) and frequency (power spectrum) domains. After analysing these snores, we were able to identify two dominant patterns which are distinctly different from each other: the "simple-waveform" and the "complex-waveform". The complex-waveform snore is characterized by repetitive, equally-spaced, train of sound structures, starting with a large deflection followed by a decaying amplitude wave. In the frequency domain, it is characterized by multiple, equally-spaced peaks of power (comb-like spectrum). Simple-waveform snores have a quasi-sinusoidal waveform, with a range of variants, and almost no secondary internal oscillations. Their power spectrum contains only 1-3 peaks, of which the first is the most prominent. We developed a mathematical representation of these waveforms, which is presented along with its implications. The complex-waveform snores result from colliding of the airway walls and represent actual brief airway closure. Simple-waveform snores are of higher frequency and probably result from oscillation around a neutral position without actual closure of the lumen.

Acoustics↗
PubMed1995

Small intestinal carcinoma with osteoclast-like giant cells.

An elderly woman underwent jejunectomy for a large, stenosing neoplasm. Histologically, we found an undifferentiated carcinoma with scattered mononuclear and multinuclear macrophages in the intestine and lymph node metastases. The multinuclear cells, being acid phosphatase-positive and CD68-immunoreactive, are referred to as osteoclast-like giant cells. Hepatic secondaries were discovered 6 months postoperatively. The patient succumbed to a chemotherapy-related septic event. We suggest that intratumoral infiltration by mononuclear and multinuclear macrophages expresses one of the body's defense mechanisms against cancer.

Carcinoma↗
PubMed1995

Electrically-activated dilator muscles reduce pharyngeal resistance in anaesthetized dogs with upper airway obstruction.

There is current controversy as to whether electrical stimulation of upper airway musculature can be used us a beneficial treatment modality in patients with obstructive sleep apnoea syndrome. Increased upper airway (UAW) muscle activity decreases UAW resistance (Ruaw) in isolated UAW of dogs. In the present study, we evaluated the effect of UAW muscle contraction on UAW patency in anaesthetized dogs in vivo breathing spontaneously through partially and completely obstructed UAW. Airflow and supraglottic pressure were measured to obtain Ruaw. Ruaw could be regulated by inhalation of a rubber balloon implanted transcutaneously in the pharyngeal submucosa to produce partial or complete obstruction. Wire electrodes were implanted bilaterally into the genioglossus (GG), geniohyoid (GH), sternothyroid (ST), and sternohyoid (SH) muscles for electrical stimulation (ES), and into the alae nasi for electromyographic (EMG) recording. Three levels of electrical stimulation were delivered to each muscle before and during partial or complete UAW obstruction. Genioglossus and geniohyoid stimulation both resulted in a significant reduction in Ruaw, which was most pronounced during partial obstruction, reducing Ruaw from 54 +/- 11 to 14 +/- 3 and from 74 +/- 12 to 31 +/- 5 cmH2O.L-1.s, respectively. At low voltage, stimulation of the genioglossus was more effective than stimulation of the geniohyoid in reducing Ruaw. Furthermore, electrical stimulation of the genioglossus but not of the geniohyoid released total obstruction. In contrast, electrical stimulation of the sternohyoid and sternothyroid produced no significant change in Ruaw. These findings demonstrate that selective UAW dilatory muscle contraction in spontaneously breathing anaesthetized dogs reduces Ruaw in the presence of UAW obstruction and releases UAW occlusion, with the genioglossus being the most effective muscle. This favours further attempts to investigate the benefits of electrical stimulation of selected upper airway muscles in the treatment of obstructive sleep apnoea syndrome.

Airway Obstruction↗
PubMed1994

Glossopharyngeal neuralgia associated with cardiac syncope and weight loss.

Glossopharyngeal neuralgia is an uncommon condition that has rarely been described in association with syncope and never with significant weight loss. A 50-year-old previously healthy woman presented with a 3-month history of episodic brief attacks of pain in the left side of her throat that were precipitated by swallowing. The spells gradually became more severe and progressed to loss of consciousness several times a day. Because of the severe pain and the recurrent episodes of syncope, the patient refused to eat and drink almost everything and thus she lost 6 kg in 2 weeks. During a typical episode of attacks, electrocardiographic monitoring demonstrated severe bradycardia and asystole for 4 second. Carbamazepine therapy (600 mg/d) completely abolished the pharyngeal pain and the associated cardiac manifestations for at least 12 months, thereby enabling rapid restoration of the lost weight.

Cranial Nerve Diseases↗
PubMed1994

Temporal arteritis associated with acute Q fever. A case report.

The authors describe the case of a sixty-four-year-old man who presented with clinical and histopathologic evidence of temporal arteritis associated with acute Q fever. This association, which has not been previously reported, supports the possible infectious etiology in temporal arteritis.

Acute Disease↗
PubMed1994

Pulmonary angiotensin converting enzyme activity in elastase induced emphysema.

Pulmonary emphysema would be expected to reduce angiotensin converting enzyme (ACE) activity due to diminished capillary bed. However, transpulmonary angiotensin conversion has been found to be unaffected or marginally reduced in emphysema. In the present study we examined the activity of ACE in an experimental model of emphysema. Vmax and Km of ACE were determined in lung homogenates of six hamsters with elastase-induced emphysema and seven control hamsters. In the emphysematous lungs, ACE activity was significantly elevated due to marked increase in Vmax (19.2 +/- 1.7 vs. 4.9 +/- 1.6 nmol/min/mg protein for emphysematous and control lungs, P < 0.01). The Km of ACE was unaffected by emphysema. We suggest that the increase in ACE activity may be an adaptive change to enable adequate metabolic activity in the face of progressive reduction in pulmonary capillary surface area in emphysema.

Amino Acid Sequence↗
PubMed1993

Effect of upper airway muscle contraction on supraglottic resistance and stability.

The activation of upper airway (UAW) muscles is believed to increase UAW patency to air flow. To evaluate the mechanisms by which UAW muscles act to prevent UAW collapse, pressure-flow relationships of the isolated UAW as well as the negative pressure required to cause UAW collapse (Pcrit) were assessed before and during electrical stimulation of four UAW muscle pairs in anesthetized dogs. Stimulation of each of the muscles shifted the pressure-flow curve toward lower pressures for any given flow rate, indicating UAW dilatation. UAW resistance decreased from 7.9 +/- 0.6 to 0.4 +/- 0.1, 2.7 +/- 0.6, 2.3 +/- 0.8 and to 4.8 +/- 1.5 cmH2O.L-1.sec during genioglossus, geniohyoid, sternothyroid and sternohyoid stimulation respectively (P < 0.01 in all cases). However, only genioglossus stimulation significantly increased Pcrit (from -3.4 +/- 0.6 to -12.0 +/- 1.8 cmH2O, P < 0.001). Relaxation of the genioglossus thus appears to produce the main impediment to air flow through the UAW, and contraction of this muscle improves UAW patency both by dilating the supraglottic airway and by stiffening its walls.

Airway Resistance↗
PubMed1993

Localized Wegener's granulomatosis relapsing as diffuse massive intra-alveolar hemorrhage.

In a 75-year-old patient presenting with a solitary pulmonary mass, a localized form of Wegener's granulomatosis was diagnosed after lobectomy. In the absence of extrapulmonary manifestations and after a benign postoperative course, the patients was discharged without medical treatment. Three months later, diffuse alveolar hemorrhage developed abruptly, necessitating mechanical ventilation, and was followed by cardiac complications and a fatal outcome. This case and another previously reported strongly suggest the need for medical treatment in patients with a localized form of pulmonary Wegener's granulomatosis, even when complete remission after surgical resection of the lung lesion seems to have been achieved.

Aged↗
PubMed1993

Cardiac arrhythmias after inhaled bronchodilators in patients with COPD and ischemic heart disease.

Selective beta 2-agonist aerosols may produce significant cardiovascular effects. In the present study we used Holter monitoring to compare the arrhythmogenic effects of inhaled terbutaline (TE), a beta 2-agonist, with that of ipratropium bromide (IB), a nonabsorbable cholinergic drug. Fourteen patients with concomitant obstructive lung disease, ischemic heart disease, and complaints of postinhalation palpitations were studied in a random, double-blind, cross-over fashion. Both drugs significantly improved vital capacity and FEV1. Heart rate and the frequency of premature beats were not significantly affected by the bronchodilators. We conclude that no clear connection between inhaled bronchodilators and arrhythmias could be demonstrated.

Administration, Inhalation↗