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Biomedical subjects

S Shore

Publications and source records attributed to S Shore.

31 records · Page 2Linked to original sources
PubMed1985

Tachyphylaxis to inhaled aerosolized histamine in anesthetized dogs.

Three consecutive dose-response curves to inhaled aerosolized histamine, separated by 1-h intervals, were obtained in 20 anesthetized mongrel dogs. In general, successive histamine dose-response curves shifted progressively rightward. Changes in pulmonary resistance (RL) and dynamic compliance (Cdyn) in response to low concentrations of histamine were reproducible, but responses to high concentrations (sufficient to at least double RL or decrease Cdyn by at least 30%) decreased on successive dose-response curves. The concentration of histamine required to double RL increased significantly (P less than 0.05) from 1.01 mg/ml on the first to 1.62 and 2.02 mg/ml on the second and third dose-response curves. In contrast, consecutive methacholine dose-response curves were not significantly different. Indomethacin pretreatment (5 mg/kg iv) prevented histamine tachyphylaxis, whereas atropine (4 mg iv) did not. However, indomethacin did not alter base-line pulmonary mechanics or histamine responsiveness as measured on the first dose-response curve. We conclude that tachyphylaxis to inhaled aerosolized histamine occurs in anesthetized dogs. Our results are consistent with an important role for endogenous prostaglandins in modulating the airway responses to repeated histamine exposures.

Aerosols↗
PubMed1983

Mechanisms of histamine-induced contraction of canine airway smooth muscle.

We studied the effects of atropine (10(-10) to 10(-6) M), tetrodotoxin (TTX) (10(-6) g/ml), and neostigmine (10(-7) M) on the histamine dose-response curve of canine tracheal smooth muscle (TSM) in vitro. Pretreatment with atropine or TTX reduced base-line tension in some TSM samples, whereas neostigmine invariably caused contraction of TSM. All concentrations of atropine reduced the maximum isometric tension produced by histamine (Tmax). With 10(-6), 10(-8), and 10(-10) M atropine, Tmax was 57, 74, and 88%, respectively, of its value in paired control samples. Atropine, 10(-9) to 10(-6) M, increased the concentration of histamine which produced 20% of Tmax, whereas 10(-6) M also increased the concentration required to produce 50% of Tmax. TTX reduced tension produced by low concentrations of histamine but had no effect at higher concentrations. Neostigmine shifted the histamine dose-response curve and caused greater tension for any given histamine concentration; Tmax increased by 30% (P less than 0.05). Our data are consistent with spontaneous release of acetylcholine from cholinergic nerves in the airway tissue and suggest that histamine either accelerates this release or interacts supra-additively with the acetylcholine at the smooth muscle.

Acetylcholine↗
PubMed1982

Reassessment of body plethysmographic technique for the measurement of thoracic gas volume in asthmatics.

We measured thoracic gas volume (Vtg) by the body plethysmographic technique in 4 normal subjects and in 9 asthmatics during remission and after bronchoconstriction induced with inhaled aerosolized histamine. Changes in both mouth (Pm) and esophageal pressure (Pes) were used to approximate changes in alveolar pressure (Palv), and both Vtg(m) and Vtg)(es) were computed. Because small changes in lung recoil occur during panting, delta Pes exceeds delta Pm, leading to a value of Vtg(m) that is slightly greater than Vtg(es). Indeed, in the normal subjects, Vtg(m) was significantly greater than Vtg(es), and the observed percentage error (E) between them (2.8%) corresponded with the expected value. In the asthmatics, during marked bronchoconstriction, there was an increased tendency for Vtg(m) to exceed Vtg(es), E averaging 12.2% and being greater than the predicted error. In some asthmatics, changes in volume led changes in Pm; the phase angle between volume and Pm averaged 6.3 degrees and was significantly greater than that between volume and Pes (1.7 degrees). In 3 asthmatics, increases in TLC(m) were not accompanied by similar changes in TLC(es). Our data are consistent with the hypothesis that when a compliant upper airway is coupled with a high airway resistance during panting against an occluded airway, transmission of changes in alveolar pressure to the mouth is incomplete. The resulting underestimation of delta Palv by delta Pm leads to artifactual increases in TLC.

Adult↗
PubMed1982

Effect of continuous positive airway pressure on respiratory mechanics and pattern of breathing in induced asthma.

We studied the effects of continuous positive airway pressure (CPAP) in 8 asthmatic subjects in whom bronchospasm was induced by aerosolized histamine. The CPAP (12.0 +/- 0.9 cm H2O) increased functional residual capacity by only 0.27 +/- 0.12 L, raised the minimal pleural pressure (Ppl) during inspiration from -32.3 +/- 2.6 cm H2O to -22.8 +/- 2.3 cm H2O (p less than 0.01), and decreased the swings in transdiaphragmatic pressure (Pdi) from 35.1 +/- 2.4 cm H2O to 29.6 +/- 3.7 cm H2O (p less than 0.05). Although ventilation (VE) increased, the inspiratory work per liter of VE fell significantly. More importantly, the pressure-time product for the inspiratory muscles (integral of Ppl.dl) measured over 60 s, fell from 830 +/- 111 to 573 +/- 41 cm H2O.s (p less than 0.05), whereas that for the diaphragm (integral of Pdi.dt) fell from 690 +/- 91 to 497 +/- 74 cm H2O.s (p less than 0.05). We conclude that in induced asthma, CPAP reduces the load on the inspiratory muscles, improving their efficiency and decreasing the energy cost of their action. Our results justify further investigation into the role of CPAP in the treatment of respiratory failure caused by severe bronchial asthma.

Abdominal Muscles↗
PubMed1980

The role of respiratory muscles in the hyperinflation of bronchial asthma.

To examine the mechanism of hyperinflation in bronchial asthma we studied lung and chest wall mechanics in 7 asymptomatic patients in whom progressive bronchoconstriction was induced by doubling the amount of inhaled aerosolized histamine. An increase in pulmonary resistance (RL) from 2.5 +/- 0.3 cmH2O . 1-1 . s (mean, +/- 1 SE) to 12.3 +/- 0.9 cmH2 was associated with a linear increase in functional residual capacity (FRC) up to 74.7 +/- 1.7% of control total lung capacity (TLCc). The mean regression coefficient was 2.3% TLCc . cmH2O-1 . 1 . s-1. At each level of hyperinflation the most positive expiratory pleural pressures measured during spontaneous breathing were generally less than the predicted chest wall relaxation pressures, indicating persistent inspiratory muscle contraction throughout expiration. This was predominantly due to inspiratory intercostal and accessory muscle activity, because measurements of transdiaphragmatic pressure indicated complete diaphragmatic relaxation early in expiration. Recruitment of abdominal muscles during expiration, inferred from measurements of gastric pressure (Pg) and abdominal antero-posterior (A-P) diameter, was progressively more apparent with increasing bronchoconstriction. We concluded that the increase in FRC in induced asthma is substantially influenced by persistent inspiratory intercostal and accessory muscle activity during expiration. Concomitant abdominal muscle recruitment results in a chest wall configuration that tends to optimize diaphragmatic function.

Abdomen↗
PubMed1979

Zinc therapy of depressed cellular immunity in acrodermatitis enteropathica. Its correction.

A child with hypogammaglobulinemia and intractable diarrhea underwent parenteral alimentation for five months. A clinical syndrome of acrodermatitis enteropathica subsequently developed associated with a depression in thymus-dependent lymphocyte (T cell) numbers, abnormal T-cell mitogen-induced blast transformation, and anergy to skin test antigens. Plasma zinc levels were found to be abnormally low. Zinc therapy resulted in dramatic resolution of the clinical manifestations of acrodermatitis enteropathica. Cell-mediated immune function was also restored to normal, suggesting an important role for zinc and possibly other trace metals in cellular immune responses.

Acrodermatitis↗
PubMed1978

Scleroderma, eosinophilia, and diffuse fasciitis.

Skin induration without internal organ involvement, blood and tissue eosinophilla, and fascilitis are features of diffuse fascilitis. However, cellular infiltrates (lymphocytes, plasma cells, and eosinophils) may also be present in the dermis, fat, and muscle. Blood eosinophilia (mild and transient) and skin eosinophilia were observed in about 20% of patients with systemic and localized scleroderma.

Adult↗