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Biomedical subjects

H Levison

Publications and source records attributed to H Levison.

At least 199 records · Page 11Linked to original sources
PubMed1976

Clinical and physiological assessment of asthmatic children treated with beclomethasone dipropionate.

Forty-two perennial asthmatic children were selected for a 12-wk study using beclomethasone dipropionate. The groups included 21 steroid-dependent children (Group I) and 21 patients (Group II) whose disease was of sufficient severity that corticosteroid therapy was contemplated. All children received the drug in a dose of 100 mug 4 times daily. During the study, oral prednisone was withdrawn from the steroid-dependent children while other therapy was essentially unchanged. Group II children underwent a double-blind trial, receiving beclomethasone for 6 wk and placebo for 6 wk. Objective assessment of adrenal and pulmonary function was obtained at regular intervals. For the latter, total lung capacity and its subdivisions, airways resistance, maximum expiratory flow volume, and oxygen tension, were measured in both groups. In Group II static elastic recoil was measured also. For most tests the results were statistically significant. In both groups, 18 of 21 patients demonstrated an excellent clinical response, no evidence of adrenal suppression, and improvement in pulmonary function. Forty of 42 patients were followed for another 12 wk, and 19 of each group did well. After 20-24 wk of therapy, 16% of patients harbored monilia in their oropharynx, and 1 patient had clinical monilial stomatitis. Within the limits of the time of the study, beclomethasone dipropionate appeared to provide adequate clinical control in many chronic, severe, steroid-dependent and nonsteroid-dependent asthmatic children.

17-Ketosteroids↗
PubMed1976

Hemoglobin-oxygen affinity in hypophosphatemic rickets.

In 14 patients with simple X-linked hypophosphatemic rickets, 5 were below the third percentile in height and 9 were between the third and twenty-fifth percentile. Although the mean serum inorganic phosphorus level was only 2.01 +/- 0.65 (normal range for all age groups is 3.8 to 6.0 mg/100 ml), both the mean values for red cell 2,3-diphosphoglycerate (2,3-DPG) and adenosine triphosphate (ATP) were normal at 4.78 +/- 1.23 and 1.02 +/- 0.17 mumol/ml of red blood cells respectively. Moreover, the mean P50 value was normal at 26.4 +/- 0.9 mmHg. These normal oxygen transport data make unlikely any proposal that short stature seen in these patients is secondary to chronic tissue hypoxia. They also indicate that the intra-erythrocytic organic phosphate levels are maintained at normal levels despite profound chronic hypophosphatemia.

Adenosine Triphosphate↗
PubMed1976

Mucociliary transport in trachea of patients with cystic fibrosis.

Mucociliary tracheal transport rates were measured in 20 patients with cystic fibrosis, in whom these rates ranged from 0 to 12.8 mm/min. The patients were divided into 3 roughly equal groups on the basis of their transport rates. (1) Those in whom no abnormality in mucociliary transport was detected in the trachea; (2) those in whom normal transport rates were measured but in whom abnormalities such as cessation, or reversal of bolus movement were observed; (3) those in whom no normal transport rates were observed. In the first group the rates were similar to those observed in a population of healthy adults. These normal rates were observed in some patients who had a productive cough. The mean mucociliary tracheal transport rate increased with increasing maximum midexpiratory flow. Those patients with a low Shwachman score and poor arterial oxygen tension tended to fall into groups 2 and 3. In the ciliary dyskinesia assay in rabbit trachea the serum from the patients with the higher transport rates tended to initiate more rapid discharge of material from the epithelium and ciliary dyskinesia.

Adolescent↗
PubMed1976

Transit time analysis of the forced expiratory spirogram in growth.

In the search for more sensitive indicators of airway obstruction Fish et al. (Am. Rev. Respirat. Diseases 109: 700, 1974) have proposed a transit time analysis of the forced expiratory spirogram. In this method the forced vital capacity (FVC) is divided into volumes of air and each volume is assigned a transit time; the nature of the FVC can be described by the transit times' mean, standard deviation, and index of skewness. In a group of 48 healthy nonsmoking subjects between the ages of 9 and 22 yr we found that all three quantities decreased with increasing age. This demonstrates an improvement in the function of the peripheral airways with lung growth. In contrast to the increase in flow rates with lung growth, none of this improved function can be attributed to increased lung volume.

Adolescent↗
PubMed1976

Effect of increased gas density on pulmonary gas exchange in man.

Pulmonary gas exchange was measured in seven resting supine subjects breathing air or a dense gas mixture containing 21% O2 in sulfur hexafluoride (SF6). The mean value of the alveolar-arterial oxygen difference (AaDO2) decreased from 12.4 on air to 7.0 on SF6 (P less than 0.01), and increased again to 13.4 when air breathing resumed (P less than 0.01). No differences occurred between gas mixtures for O2 consumption, respiratory quotient, minute ventilation, breathing frequency, heart rate, or blood pressure, and the improved oxygen transfer could not be attributed to changes in cardiac output or mixed venous oxygen content in the one subject in which they were measured. These results are best explained by an altered distribution of ventilation during dense gas breathing, so that the ventilation-perfusion ratio (VA/Q) variance was reduced. Of several considered mechanisms, we favor one in which SF6 promotes cardiogenic gas mixing between peripheral parallel units having different alveolar gas concentrations. This mechanism allows for observed increases in arterial carbon dioxide tension and dead space-to-tidal volume ratio during dense gas breathing, and suggests that intraregional VA/Q variance accounts for at least one-half of the resting AaDO2 in healthy supine young men.

Blood Gas Analysis↗
PubMed1976

Protease inhibitors in patients with chronic obstructive pulmonary disease: the alpha-antitrypsin heterozygote controversy.

A group of 163 patients with chronic obstructive pulmonary disease, from the pulmonary service of a large urban hospital, were evaluated for their protease inhibitor (Pi) type by starch gel and crossed immunoelectrophoresis, for serum concentrations of alpha1-antitrypsin and alpha1-antichymotrypsin, and for pulmonary function. Of the patients with emphysema, 17.8% were of Pi type Z; 50% of these were less than 45 years of age, compared to 13% of those of Pi type M. Of all patients with chronic obstructive pulmonary disease, 4.9% were of Pi type Z; 4.9% of patients were of Pi type MZ (heterozygotes) compared with 1.9% of the control population. There was an increased incidence of chronic obstructive pulmonary disease in persons of Pi type MZ, but no increase in persons of Pi type MS. Concentrations of both alpha1-antitrypsin and alpha1-antichymotrypsin were increased and were correlated. No patient had a deficiency of alpha1-antichymotrypsin.

Adult↗
PubMed1976

Transit time analysis of the forced expiratory vital capacity in cystic fibrosis.

Transit time analysis of the forced expiratory vital capacity maneuver was applied to 37 patients with cystic fibrosis 8 to 22 years of age. This analysis divides the vital capacity into segments of air and assigns a transit time to each segment. The characteristics of the distribution of these transit times are used as measurements of pulmonary function. The quantities were compared with the forced vital capacity, 1-sec forced expiratory volume, ratio of 1-sec forced expiratory volume to vital capacity, peak flow, forced expiratory flow during the middle half of the forced vital capacity, maximal expiratory flow at 25 per cent of the vital capacity, specific airway conductance, and arterial PO2 of these patients. The standard deviation of the transit times was the most frequently abnormal. The mean transit time had the largest range of values in terms of its own standard deviation, and it was the best single estimate of over-all lung function because it correlated almost equally with large and small airway function. The coefficient of cariance of transit times was specific in detecting abnormality of small airways and was as sensitive in the detection of minimal lung disease as the standard deviation of transit times.

Adolescent↗
PubMed1976

Five- to seven-year course of pulmonary function in cystic fibrosis.

The pulmonary function records of 132 patients with cystic fibrosis followed for 5 to 7 years were reviewed. Changes in forced vital capacity, 1-sec forced expiratory volume, mean forced expiratory flow during the middle half of the forced vital capacity, and 1-sec forced expiratory volume as a percentage of forced vital capacity were examined. There was considerable variation in the rates of change, but the general pattern was consistent with a theory of exponential decline, mean forced expiratory flow during the middle half of the forced vital capacity showing the earliest and most dramatic changes. The pulmonary function of 33 patients (25 per cent) remained stable or improved throughout follow-up, possibly reflecting mild forms of lung disease or the efficacy of therapy. Twenty of these patients (15 per cent) maintained completely normal pulmonary function. The rate of decline in pulmonary function values, with progress of the disease, was steeper in the female patients.

Adolescent↗
PubMed1976

The ventilatory response to carbon dioxide in asthmatic children, measured by the mouth-occlusion method (Pm100).

Ventilatory responses to carbon dioxide vary widely in patients with bronchial asthma; some have a high response despite increased airway resistance. This paradoxical response was studied in 31 asthmatic children and 22 age-matched healthy children. Measurement of the ventilatory response to carbon dioxide with a conventional rebreathing method showed wide variation in the patients, paralleling the degree of their airway obstruction as measured by the one-second forced expiratory volume and maximal midexpiratory flow rate, but their mean response was similar to that in the control subjects. The ventilatory response was then determined with a new index (Pm100), which rises linearly with increasing carbon dioxide concentration. Despite wide variation in the slope of Pm100 in the patients, their mean response significantly exceeded normal, confirming that the neurochemical drive is increased in bronchial asthma.

Adolescent↗
PubMed1976

Physical signs in childhood asthma.

In 62 children with bronchial asthma, the presence of subjective dyspnea and wheeze, and some physical signs commonly associated with chronic obstructive airway disease in older patients, were compared with results of routine pulmonary function tests. Overall, airway resistance and the relationships of residual volume and functiona residual capacity to total lung capacity were increased and other measurements of pulmonary function were moderately decreased. The time-honored subjective dyspnea, wheeze, rhonchi, and prolonged expiration were least useful as indices of severity of disease. Most of the patients, particularly those in whom laboratory testing revealed marked impairment, had notable rhonchi, prolonged expiration, scalene muscle and sternocleidomastoid contraction, and supraclavicular indrawing. Only sternocleidomastoid contraction and supraclavicular indrawing clearly correlated with the severity of airway obstruction. A call is made for a search for these useful signs, whose presence may be the only clue to moderately severe disease; however, their absence does not guarantee absence of severe airway obstruction.

Adolescent↗
PubMed1975

Mucociliary tracheal transport rates in man.

A new method for measuring mucociliary tracheal transport rates (MTTR's) is described. An aqueous aerosol containing albumin microspheres labeled with 99mTc was inhaled in such a manner that it was deposited in local concentrations in the large airways. These boli of microspheres were transported up the trachea and their MTTR's measured using a gamma camera. MTTR's were measured in 42 healthy nonsmoking adults (32 men and 10 women, mean age 28 yr). The mean MTTR's appeared to be log normally distributed with a geometric mean of 3.6 mm/min and a coefficient of variation of 75%. The MTTR's of men and women were similar. Each individual's short-term coefficient of variation was 25%. Twenty-two repeat studies 1 wk to 15 mo apart showed the variation within individuals was less than between individuals. The parasympatholytic drug, atropine (0.6 mg iv) decreased MTTR's for at least 3 h. Inhalation of the sympathomimetic drug, Th1165a increased MTTR's. Chronic and acute smoking did not appreciably change the MTTR'S.

Adrenergic beta-Agonists↗
PubMed1975

A new method of evaluating the chemosensitivity of the respiratory center in children.

Decreased ventilatory response to carbon dioxide is often present in lung disease. This can be due to a reduction in the output of the respiratory center or an inability of the respiratory pump to respond to a normal output because of the size or impedence of the pump. To separate these mechanisms we have measured the isometric force developed by the respiratory muscle during brief airway occlusion, by measuring the pressure generated at 100 msec (Pm100). We studied 43 subjects ranging in age from 6 to 50 years, and nine neonates. We found a linear rise of Pm100 with rising PAco2 during carbon dioxide rebreathing maneuvers. Our results also show that although there are wide variations in slopes of Pm100 to carbon dioxide tension (SPm100/PAco2) between individuals, in a given subject this slope remains constant even following repeated studies. It also remains constant for age and size, indicating that the neuromechanical output of the respiratory apparatus does not change with growth. In contrast the ventilatory response either assessed as Ve/PAco2 or Vt/PAco2 depended on age and lung size. The results suggest that throughout growth, comparison of Pm100/PAco2 and Ve/PAco2 can distinguish between abnormalities of neuromuscular output from other causes of ventilatory impairment.

Adolescent↗