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Biomedical subjects

M Littner

Publications and source records attributed to M Littner.

32 records · Page 2Linked to original sources
PubMed1985

Conservation of oxygen supply using a reservoir nasal cannula in hypoxemic patients at rest and during exercise.

A reservoir nasal cannula which stores oxygen during exhalation and delivers it as a bolus during inhalation has been reported to conserve oxygen delivery in patients with chronic obstructive pulmonary disease (COPD) at rest. We compared the effects upon arterial oxygen saturation (SaO2) of the reservoir cannula and a standard nasal cannula in hypoxemic obstructed and restricted patients at rest and during exercise. The SaO2 was monitored by ear oximeter. While at rest, 13 obstructed and four restricted patients breathed oxygen from the reservoir cannula at 0.5, 1.0, 1.5, and 2.0 L/min and from a standard cannula at 0.5, 1.0, 2.0, 3.0, and 4.0 L/min. Mean SaO2 was significantly higher with the reservoir cannula compared to the standard cannula at 1.0 and 2.0 L/min (p less than 0.0006) and tended to be higher at 0.5 L/min (p less than 0.1). Seven obstructed patients walked on a level treadmill at 0.75 mph while breathing oxygen at 0.5 and 1.5 L/min from the reservoir cannula and at 1.0 and 3.0 L/min from the standard cannula. The SaO2 during exercise with the reservoir cannula was comparable to that with the standard cannula at approximately half of the oxygen flow rate. The ratio of the oxygen flow rate of the standard to the reservoir cannula to produce 90 percent saturation was estimated and found to be 2.5 +/- 0.8 (mean +/- SD) for patients at rest and 2.9 +/- 1.8 during exercise. We conclude that in hypoxemic patients at rest and during exercise, the reservoir cannula uses less than half the oxygen of a standard cannula to produce similar improvement in SaO2 and thus has advantages of a reduced cost of ambulatory therapy with low-flow oxygen and a longer time permitted away from a stationary source of oxygen.

Carbon Dioxide↗
PubMed1984

Awake abnormalities of control of breathing and of the upper airway. Occurrence in healthy older men with nocturnal disordered breathing.

We hypothesized that preexisting diminished chemical control of breathing and narrowing of the upper airway are associated with sleep-related disordered breathing (SRDB) in healthy older men. Twenty-six subjects, aged 55 to 70, were studied. An SRDB episode was a decrease in arterial oxygen saturation (SaO2) of at least 4 percent. Some of these episodes occurred while airflow continued (ie, nonapneic episodes), and the rest occurred with apnea. Sixteen subjects had greater than 12 SRDB episodes per hour of sleep (SRDB subjects) and ten subjects had less than 8 episodes per hour (controls). During waking, the mean hypercapnic ventilatory response was lower, and the mean supine nasal airway resistance (SNAR) was higher in SRDB subjects than in control subjects. During waking, 12 of 16 SRDB subjects had one or more respiratory abnormalities: four had an elevated SNAR; four had a reduced hypercapnic response; three had a reduced hypoxic ventilatory response, and two had an abnormal flow-volume curve. Only one of ten control subjects had a respiratory abnormality (an elevated SNAR). Also, the number of SRDB episodes per hour correlated with the SNAR, and the minimum SaO2 during sleep correlated with the magnitude of the hypercapnic response. We conclude that SRDB occurs commonly in otherwise healthy older men with preexisting abnormalities of control of breathing or of the upper airway.

Age Factors↗
PubMed1983

Cyclooxygenase products and cyclic nucleotide levels with infusion of arachidonic acid, PGI2, PGE2, PGF2, and 6-keto-PGF1 in an isolated dog lung.

Arachidonic acid (AA) was infused into the pulmonary artery of an isolated dog lung perfused with a physiologic salt solution. This led to elevations in pulmonary cyclic AMP and prostaglandins (PGs) including PGE2, PGF2 alpha, TXB2 (a metabolite of TXA2), and 6-keto-PGF1 alpha (a metabolite of PGI2). The elevations were prevented by PG synthesis inhibitors. A dose of PGI2 comparable to that produced from AA led to elevations in cyclic AMP. These elevations were not reduced by PG synthesis inhibitors; this indicated that the inhibitors did not reduce cyclic AMP except by inhibiting metabolism of AA. The PGE2 led to lesser elevations in cyclic AMP than did PGI2; PGF2 alpha and 6-keto-PGF1 alpha did not increase cyclic AMP. Levels of cyclic AMP were not elevated. We conclude that some of the elevation in cyclic AMP from AA was most likely from production of PGs since elevations in both were prevented by the inhibitors. However, the possibility remains that AA metabolites other than PGs also contributed to elevations in cyclic AMP. We also conclude that PGI2 most likely accounted for some of the cyclic AMP elevation from AA since PGI2 could be readily produced in amounts that elevate cyclic AMP. However, the possibility remains that PGE2, the less consistent cyclic AMP stimulators (l.e., PGF2 alpha and 6-keto-PGF1 alpha), TXA2 or TXB2, or PGs not measured in this study also contributed to the elevations in cyclic AMP from AA.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Sleep related breathing disorders in older men: a search for underlying mechanisms.

The incidence of sleep-related breathing disorders (SRBDs) associated with hemoglobin desaturation was determined by nocturnal polygraphic evaluations in 26 healthy men, aged 55-70 years. Sixteen subjects (62%) had abnormal rates of at least 12 episodes per hour of sleep: 8 had occlusive, and 8 had central apnea or hypopnea. During waking ten of 16 SRBD subjects and only one subject without SRBDs exhibited either an elevated nasopharyngeal airway resistance (n = 4) or a reduced ventilatory response to hypercapnia (n = 4) and/or hypoxia (n = 3). However, these abnormalities were not related to the type or severity of SRBDs, and 6 subjects with SRBDs demonstrated no respiratory defect. We conclude that SRBDs have a very high incidence in older males and are not usually secondary to pulmonary cardiac, neurological, or behavioral disorders. Additionally, we hypothesize that abnormalities in ventilatory control or upper airway resistance contribute to SRBDs, but depression of brain stem reticular formation activity during sleep plays a primary role in these disorders. Factors related to both aging and SRBDs are reviewed. These include reduced chemoreceptor responses, altered steroid hormone metabolism, and use and metabolism of hypnotic drugs and alcohol.

Aged↗
PubMed1982

Subsensitization of beta-adrenoceptors in airways and lymphocytes of healthy and asthmatic subjects.

Subsensitization of beta-adrenoceptors in airways and lymphocytes developing during 4 to 5 wk of orally administered terbutaline (a long-acting beta 2 selective bronchodilator) was compared in 10 healthy subjects and 11 subjects with mild asthma. The following results were obtained. Normal subjects developed a significant reduction in acute bronchodilator responsiveness to inhaled isoproterenol but not to subcutaneously administered terbutaline. The subjects with asthma failed to develop any alteration in responsiveness to either inhaled isoproterenol or subcutaneously administered terbutaline. None of 5 normal or 4 asthmatic subjects studied demonstrated any significant change in sensitivity to histamine-induced bronchospasm or any significant decrease in the acute protective effect of subcutaneously administered terbutaline against histamine-induced bronchospasm. Marked and significant decreases occurred in the density of lymphocyte beta-receptor sites in both groups. Maximal isoproterenol-stimulated cyclic AMP responses in lymphocytes from normal subjects were reduced, but in asthmatics, in whom the baseline values were lower to begin with, a similar decrease was not observed. In most instances, the number of receptor sites returned to normal within 2 wk after cessation of terbutaline. A single dose of methylprednisolone caused a return to normal values within 16 h. We conclude that chronic therapy with an oral beta 2-adrenostimulant, although producing striking and significant down-regulation of beta-adrenergic receptors of peripheral lymphocytes, does not lead to physiologically detectable beta-adrenoceptor subsensitivity in the airways of asthmatics or to consistent subsensitivity in the airways of healthy persons.

Adolescent↗
PubMed1982

Airway reactivity and exercise in healthy subjects.

The interaction of exercise, methacholine challenge, and beta-adrenergic blockade was investigated in eight healthy subjects. We measured the response to increasing doses of aerosolized methacholine, examining maximum expiratory flow rates. These responses were compared with those obtained on separate days when each methacholine challenge followed submaximal exercise or submaximal exercise in the presence of Beta-blockade. The possible independent effect of increased ventilation (20 +/- 6.7 L/min) was also studied during methacholine challenge. Methacholine-induced bronchospasm was not augmented by exercise alone or by exercise in the presence of beta-blockade, nor was this response significantly altered by hyperventilation during methacholine aerosol challenge. These findings suggest that airway hyperreactivity cannot be induced in healthy subjects by levels of exercise that commonly provoke exercise-induced bronchospasm in asthmatic patients.

Adult↗
PubMedDate not supplied

Dissociation of 24-hour catecholamine levels from blood pressure in older men.

Increased plasma norepinephrine levels have been observed in some persons with early essential hypertension. Although both plasma norepinephrine level and mean arterial blood pressure rise with age, little is known about the state of catecholamine secretion in elderly patients with essential hypertension. We studied the 24-hour cycle levels of plasma norepinephrine, epinephrine, and dopamine in 12 elderly hypertensive subjects and 13 age-matched normotensive controls (mean ages, 63.8 +/- 1.2 yr and 64.8 +/- 1.8 yr [SEM] respectively). Blood samples were obtained at bihourly intervals from 0900 to 2100 hours and every 30 minutes from 2100 to 0900 hours, during which time sleep and breathing were continuously monitored. A circadian rhythm was displayed in both groups by plasma epinephrine levels (mesor, 49 +/- 2 pg/ml and 38 +/- 1 pg/ml; amplitude, 15 +/- 2 pg/ml and 11 +/- 1 pg/ml; acrophase, 12.20 +/- 0.40 hr and 14.41 +/- 0.34 hr in the normotensive and hypertensive groups respectively) but not by plasma norepinephrine or dopamine levels. During the 24-hour cycle plasma epinephrine, but not norepinephrine or dopamine, levels were positively related to mean arterial blood pressure (r = 0.60 for the normotensive subjects, r = 0.57 for the hypertensive subjects, p less than 0.01 for both).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMedDate not supplied

Effect of age on circadian rhythm of prolactin in normal men.

The 24 h secretion pattern of prolactin was studied in 9 young normal males (aged 22-46) and in 11 older normal men (aged 55-74). Despite considerably reduced duration and quality of sleep, the nocturnal surge in plasma prolactin in elderly men was the same as in young subjects. The overall 24 h secretion pattern and the absolute levels of prolactin are unaltered with age in normal men.

Aging↗
PubMedDate not supplied

A study of small superficial capillary hemangiomas on the lips in children.

PURPOSE: This study describes 77 small vascular lesions on the lips of 74 children and adolescents. RESULTS: Of the 77 lesions, 70% were on the lower lip and 30% on the upper. The diameter range was 0.5-5.0 mm (mean 1.4 mm). On both lips the lesions were in the vermilion zone, close to the border with the skin. The surface of the lesions was smooth and slightly raised, and varied in color from red (49%) through bluish red (45%) to purple (6%). The borders were well defined in most cases. The histology of the lesions was consistent with capillary hemangioma. Small superficial capillary hemangiomas (SSCH) in this study behaved differently from most hemangiomas and vascular malformations in that they did not increase in size, and were persistent in the age group in which most hemangiomas are reported to involute or disappear. The gender distribution of SSCH also differed from the female predominance in hemangioma. SSCH is a solitary benign lesion on the lips of children and adolescents, which has not been separately classified before. CONCLUSIONS: Based on the differences from hemangioma in gender distribution, size, border definition, and growth characteristics, it is suggested that SSCH be classified as a variant or a subgroup of hemangioma.

Adolescent↗