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Biomedical subjects

K Desmond

Publications and source records attributed to K Desmond.

16 recordsLinked to original sources
PubMed2006

Jamming of three-dimensional prolate granular materials.

We have found that the ability of long thin rods to jam into a solidlike state in response to a local perturbation depends upon both the particle aspect ratio and the container size. The dynamic phase diagram in this parameter space reveals a broad transition region separating granular stick-slip and solidlike behavior. In this transition region the pile displays both solid and stick-slip behavior. We measure the force on a small object pulled through the pile, and find the fluctuation spectra to have power law tails with an exponent characteristic of the region. The exponent varies from beta=-2 in the stick-slip region to beta=-1 in the solid region. These values reflect the different origins--granular rearrangements vs dry friction--of the fluctuations. Finally, the packing fraction shows only a slight dependence on container size, but depends on aspect ratio in a manner predicted by mean-field theory and implies an aspect-ratio-independent contact number of =5.25 +/- 0.03.

Journal Article↗
PubMed1998

Life after breast cancer: understanding women's health-related quality of life and sexual functioning.

PURPOSE: To describe the health-related quality of life (HRQL), partner relationships, sexual functioning, and body image concerns of breast cancer survivors (BCS) in relation to age, menopausal status, and type of cancer treatment. PATIENTS AND METHODS: A cross-sectional sample of BCS in two large metropolitan areas was invited to participate in a survey study that included the following standardized measures: the RAND 36-Item Health Survey; the Centers for Epidemiologic Studies-Depression Scale (CES-D); the Dyadic Adjustment Scale (DAS); the Breast Cancer Prevention Trial (BCPT) Symptom Checklist; the Watts Sexual Functioning Questionnaire (WSFQ); and subscales from the Cancer Rehabilitation Evaluation System (CARES). RESULTS: Eight hundred sixty-four BCS completed the survey. RAND Health Survey scores were as good or better than those of healthy, age-matched women, and the frequency of depression was similar to general population samples. Marital/partner adjustment was similar to normal healthy samples, and sexual functioning mirrored that of healthy, age-matched postmenopausal women. However, these BCS reported higher rates of physical symptoms (eg, joint pains, headaches, and hot flashes) than healthy women. Sexual dysfunction occurred more frequently in women who had received chemotherapy (all ages), and in younger women who were no longer menstruating. In women > or = 50 years, tamoxifen therapy was unrelated to sexual functioning. CONCLUSION: BCS report more frequent physical and menopausal symptoms than healthy women, yet report HRQL and sexual functioning comparable to that of healthy, age-matched women. Nevertheless, some survivors still experience poorer functioning, and clinicians should inquire about common symptoms to provide symptomatic management or counseling for these women.

Aged↗
PubMed1994

Effect of caffeine on the ventilatory response to inhaled carbon dioxide.

We investigated the effect of caffeine on the hypercapnic ventilatory response (HCVR) using steady state (SS) and rebreathing (RB) methods in 6 subjects. They received caffeine (5 mg/kg) or saline intravenously in a randomized, double-blind, crossover manner, with measurement of serum caffeine levels. PETCO2 and (VE), normalized for vital capacity (VC), were measured continually during RB and during the last 5 min of SS runs. The slope of the VE-PETCO2 response increased from 0.21 +/- 0.14 to 0.38 +/- 0.14 and from 0.23 +/- 0.12 to 0.59 +/- 0.45 VC.min-1.mmHg-1, measured by RB and SS respectively (P < 0.05). Plotting VT vs PETCO2 revealed a parallel shift (additive effect) in the response measured by RB after caffeine; but an increased slope (multiplicative effect) in the VT-PETCO2 relation measured in SS. We conclude that caffeine acts as a respiratory stimulant and increases the HCVR, but that assessment of the caffeine-CO2 interaction is dependent on the methodology employed.

Administration, Inhalation↗
PubMed1991

Measurement of respiratory system resistance by forced oscillation in normal children: a comparison with spirometric values.

In 377 children, the commercially available Siregnost FD-5 was used to measure respiratory system resistance (Rrs) by forced oscillation at 10 Hz. The children were between 3 and 18 years of age and, by a detailed questionnaire and conventional pulmonary function testing in 335, they were shown to be representative of the normal pediatric population. There was a linear relationship between Rrs and height (Rrs = 13.9-0.064 x ht (cm), r = -0.87). Children less than 6 years of age had no trouble with using the forced oscillation technique. The smoking of tobacco in the house, the presence of carpets in the child's bedroom, or an atopic family history, alone or in combination, had no influence on Rrs or on any spirometric measure. Forced oscillation is useful in children too young to be able to cooperate with conventional pulmonary function testing.

Adolescent↗
PubMed1991

The effects of diuresis and transfusion on pulmonary function in children with thalassemia major.

Previous pulmonary function studies in subjects with thalassemia major (TM) who were on regular transfusion programs have demonstrated results ranging from small airway obstruction to a restrictive pattern. Ten subjects with TM were studied pre- and postdiuresis, and again 24 hr after transfusion, in order to evaluate the role of possible fluid overload in altering pulmonary function. Subjects underwent spirometry and had lung volume and flow volume curves (MEFVC) measured in a volume displacement plethysmograph while breathing air and a mixture of 80% helium and 20% oxygen (HeO2). Six patients had pulmonary mechanics measured with esophageal balloons in place. Baseline function was normal and no change occurred following diuresis. Following transfusion, the volume of isoflow (VisoV) decreased, but other parameters did not change. Subsequent analysis revealed 5 subjects with an initial VisoV greater than 20 (% FVC) but, paradoxically, less evidence of flow limitation in the small airways than those with a VisoV less than 20 (% FVC). Posttransfusion, in those subjects with an initially high VisoV, the Vmax25(air) tended to fall without a change of MEFVC in HeO2, resulting in a decreased VisoV. This was interpreted as evidence of subtle abnormalities in the small airways caused by volume expansion, raising doubts about the value of the VisoV as a measure of small airway disease. As a group, our subjects did not demonstrate any abnormalities in baseline function. Some subjects had mild flow limitation in small airway while other developed comparable levels of flow limitation following the volume expansion associated with transfusion.

Blood Transfusion↗
PubMed1988

The effects of chronic airflow limitation, increased dead space, and the pattern of ventilation on gas exchange during maximal exercise in advanced cystic fibrosis.

Although exertional hypercapnea has been observed in patients with advanced cystic fibrosis (CF), the causes have not been fully elucidated. In 14 patients aged 15 to 35 yr of age with advanced CF, the effects of chronic airflow limitation (CAL), increased physiologic dead space (VD), and the timing components of ventilation (VE) on gas exchange during maximal exercise were assessed. The patients were divided into those who retained CO2 during exercise, the CO2R group, and those who did not, the CO2NR group. CO2 retention was defined as a rise in end-tidal CO2 tension of 5 mm Hg or more or to a value greater than 50 mm Hg during a progressive exercise test on a cycle ergometer. CO2 retention occurred in half the subjects, usually by the halfway mark of the test, and did not rise progressively as exercise continued. It was associated with a low VE caused by a low tidal volume (VT) that was the result of a short inspiratory time to total respiratory time ratio (0.33 +/- 0.03 versus 0.38 +/- 0.04, p less than 0.02), whereas there was no difference in mean inspiratory flow or respiratory rate. Although the CO2R group had the worst CAL, with a FEV1 of 28 +/- 7 versus 41 +/- 12% predicted (p less than 0.5) and a FVC of 42 +/- 12 versus 61 +/- 9% predicted (p less than 0.01), the VT at maximal work expressed as a percentage of FVC was lower (45 +/- 13 versus 60 +/- 11, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Effects of nutritional status on exercise performance in advanced cystic fibrosis.

Initial evaluation of 22 patients with cystic fibrosis (CF) on entry into a trial of home oxygen therapy was used to elucidate the possible effects of poor nutritional status on exercise performance in CF. The patients had advanced lung disease (mean FEV1, 36 percent predicted) and all had a stable resting PaO2 less than or equal to 65 mm Hg. Nutritional status was determined by calculating weight as a percentage of ideal for height (Wt/Ht) for each subject. Exercise testing consisted of a progressive exercise test on a cycle ergometer to measure maximum work capacity (Wmax), and a steady state test at 50 percent of baseline Wmax. During the steady state test, cardiac output (Q) and stroke volume (SV) were computed by the indirect Fick (CO2) method. Wmax, SV, Q and lung function results are expressed as percent predicted. Mean (+/- SD) Wmax was 58 +/- 15 percent predicted. Wmax correlated with both FEV1 and Wt/Ht, but FEV1 and Wt/Ht were not related. During steady state exercise, 12 of 22 patients had a SV less than 80 percent predicted. SV correlated with Wt/Ht, but not with lung function. Thirteen of the 22 patients had a Wt/Ht less than or equal to 90 percent and were considered malnourished. When compared with the well-nourished patients (Wt/Ht greater than 90%), these malnourished subjects had significantly lower mean values for Wmax%, SV% and Q% predicted, but not for lung function parameters. We conclude that: in patients with CF and advanced lung disease, nutritional status plays a significant role in determining exercise capacity; lower exercise tolerance of malnourished patients is an independent effect, as nutritional status and lung function were not related; and malnourished patients with CF have an altered cardiac performance on exercise testing which is due to a reduced SV rather than an impaired heart rate response.

Adolescent↗
PubMed1986

Knowledge of cystic fibrosis in patients and their parents.

A standardized questionnaire was used to assess knowledge about cystic fibrosis in 28 patients with cystic fibrosis (aged 10 to 21 years) and in the parents of 25 of these patients. Knowledge of disease pathophysiology and treatment was generally comprehensive and detailed; knowledge of the genetics was fair. However, there were conspicuous deficits in the awareness of reproductive risks and of male sterility. Significant predictors of patient knowledge were patient age, sex, and educational level and parental age. Predictors of parent knowledge were Shwachman score, socioeconomic status, and sex of responding parent. Patients rely heavily on parents for information about cystic fibrosis. More than one third of both patients and parents sought more information about the disease and its implications.

Adolescent↗
PubMed1982

Oxygen therapy and long-term pulmonary outcome of respiratory distress syndrome in newborns.

A previous report has shown no difference between the clinical outcome of infants exposed to a high oxygen (O2) regimen and those exposed to a low O2 regimen for the treatment of respiratory distress syndrome (RDS). Mechanical ventilation was not used in either group. In the present study, pulmonary function tests were performed on 14 survivors receiving the low O2 regimen (low O2 group) and on nine receiving the high O2 regimen (high O2 group) ten years after their initial illness. Similar evidence of abnormalities of large airways was found in both groups of prematurely born children that was comparable with that previously reported for normal prematurely born children. There was evidence in the high O2 group similar to that reported for ventilated survivors with RDS exposed to a high concentration of O2. From these data, it was concluded that neonatal exposure to high O2 concentrations in the absence of mechanical ventilation is capable of causing long-term change in small airways.

Airway Resistance↗
PubMed1982

The effect of digoxin on exercise capacity and exercising cardiac function in cystic fibrosis.

The ability of digoxin to increase exercise capacity and stroke volume (SV) during exercise was evaluated in ten patients with cystic fibrosis (CF) ages 12 to 20 years with moderate to severe degrees of airway obstruction but no history of heart failure. A double-blind crossover trial of digoxin versus placebo was carried out. An evaluation of exercise performance was undertaken upon entry into the study, and after each of the one-week periods in which digoxin 0.25 mg/day or placebo was taken. Exercise testing consisted of a progressive exercise test on a cycle ergometer to measure maximum work capacity (Wmax) and a steady state test at 2/3 of the baseline Wmax. During the steady state test, the oxygen consumption and carbon dioxide production were measured and cardiac output (Q) was calculated by the indirect Fick (CO2) method. From Q and heart rate (HR), SV was derived. After digoxin, Wmax was unchanged. On steady state exercise HR was unchanged, but there was a slight but significant fall in Q due to a fall in SV. The decrease in SV was associated with exercising hypoxemia. We conclude that digoxin did not increase exercise capacity or improve exercising cardiac function in patients with moderate to severe airway obstruction due to CF.

Adolescent↗
PubMed1982

alpha-Fetoprotein and cystic fibrosis.

Because of unconfirmed reports that the serum level of alpha-fetoprotein (AFP) is high in children with cystic fibrosis and intermediate in their siblings and parents, this level was measured in 25 children with cystic fibrosis, 26 of their siblings, 42 of their parents and 31 age-matched children without cystic fibrosis who were attending outpatient clinics of the Montreal Children's Hospital. Liver function tests were performed at the same time since patients with liver disease may have unusually high serum AFP levels and patients with cystic fibrosis often have liver involvement. AFP was not detected in any of the serum samples, and the results of the liver function tests were normal in all but 1 individual, a control subject. In simultaneous assays of serum from children with ataxia telangiectasia, however, high AFP levels were detected in 15 of 16 samples. Thus, measurement of the serum AFP level is of no value in detecting carriers of the cystic fibrosis gene.

Adolescent↗
PubMed1980

Is anti-Pseudomonas therapy warranted in acute respiratory exacerbations in children with cystic fibrosis?

A controlled study was designed to clarify the indications for antibiotic therapy in children with advanced cystic fibrosis hospitalized with respiratory exacerbations. Twenty-two children with severe CF and signs of acute lower respiratory infection were randomly assigned to receive either cloxacillin or carbenicillin plus gentamicin administered intravenously for ten days. Other aspects of therapy were constant. The groups were comparable in all respects and Pseudomonas aeruginosa was the predominant sputum pathogen in most patients. Clinical improvement, chest radiograph changes, evidence of airway obstruction, and bacteriologic flora of sputum were no different regardless of the regimen used. These results suggest that the use of anti-Pseudomonas medication in these children may not always be necessary. These observations need to be confirmed by blind-controlled studies in larger numbers of patients with mild as well as severe respiratory involvement.

Carbenicillin↗
PubMed1980

Upper airway obstruction in children. The value of inspiratory-expiratory flow-volume curves.

The physiological assessment of upper respiratory tract obstruction using inspiratory-expiratory flow-volume curves is a valuable non-invasive procedure in children. The technique employed at the Montreal Children's Hospital with appropriate case material is presented. Although flow-volume curves can reliably diagnose and localize a large airway obstruction, these lesions are readily monitored by spirometric testing.

Airway Obstruction↗
PubMed1978

Long-term pulmonary sequelae of the Wilson-Mikity syndrome.

Five children born prematurely, eight to ten years ago, who survived the Wilson-Mikity syndrome were compared with six apparently normal prematurely born children and eight normal children born at term, by means of flow volume curves obtained while breathing air and while breathing a mixture of 80% helium and 20% oxygen. The flow rates in air of the group who survived the Wilson-Mikity syndrome were significantly lower than those of the prematurely born normal children (P less than 0.01), and than those of the eight normal children (P less than 0.001). The volume of isoflow while breathing air compared to that while breathing HeO2 was highly variable, but not significantly different in the three groups. Three of the five survivors of the Wilson-Mikity syndrome had a marked concavity in the shape of their flow volume curves. It is concluded that these abnormalities are due to focal increases of compliance or resistances or both of terminal lung units and result in adjacent areas of the lung emptying at different rates. The relationship between physiologic and anatomic abnormalities seen at autopsy in those who die to the disease suggests that they are due to the same pathologic process. Whether or not these abnormalities will disappear with future lung growth remains to be seen.

Female↗
PubMed1977

Long-term pulmonary sequelae of premature birth with and without idiopathic respiratory distress syndrome.

Seven children born prematurely who survived the respiratory distress syndrome, seven children born prematurely who had no neonatal lung disease, and seven normal children born at term were studied by comparison of flow volume curves obtained while breathing air to those obtained while breathing 80% helium and 20% oxygen. Expiratory flow rates in air both groups of prematurely born children were lower than flow rates of the children born at term, and the volumes of iso-flow were higher in the survivors of RDS than those of the children born at term. The differences in flow rates in air suggest an increase in large airway resistance in both groups of prematurely born children. It is speculated that this may be secondary to growth retardation related to prematurity. The elevated Viso V in the RDS group suggests an increase in small airway resistance secondary to the disease or to its therapy.

Airway Resistance↗