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Biomedical subjects

M G Cline

Publications and source records attributed to M G Cline.

At least 19 recordsLinked to original sources
PubMed2000

Execution of the auxin replacement apical dominance experiment in temperate woody species.

The classic Thimann-Skoog or auxin replacement apical dominance test of exogenous auxin repression of lateral bud outgrowth was successfully executed in both seedlings and older trees of white ash, green ash, and red oak under the following conditions: (1) decapitation of a twig apex and auxin replacement were carried out during spring flush, (2) the decapitation was in the previous season's overwintered wood, and (3) the point of decapitation was below the upper large irrepressible lateral buds but above the lower repressible lateral buds. Although it has been suggested that neither auxin, the terminal bud, nor apical dominance have control over the outgrowth of the irrepressible buds during spring flush, there is evidence in the present study that indicates that such control over the repressible buds exists. In seedlings, second-order branching, which resulted from decapitation of elongating current shoots, was also inhibited by exogenous auxin in the three species. Hence, the auxin replacement experiments did work on year-old proleptic buds (of branches of older trees) that would have entered the bud bank and also on current buds of seedlings. Cytokinin treatments were ineffectual in promoting bud growth.

Journal Article↗
PubMed1996

Early childhood respiratory symptoms and the subsequent diagnosis of asthma.

BACKGROUND: Respiratory symptoms are frequent in very young children, and the relation of these symptoms to later asthma in some of these children is unknown. OBJECTIVE: The aim of the study was to describe the natural history of respiratory symptoms in a community-based sample of young children who were prospectively observed for as long as 11 years. METHODS: Subjects were participants in the Tucson Epidemiologic Study of Airways Obstructive Disease. They were under 5 years of age at enrollment and were studied by means of a parent-administered mail survey instrument every 1 to 2 years for 3 to 11 years. RESULTS: Among subjects younger than 1 year of age, no single respiratory symptom, such as cough or wheeze only with colds, significantly increased the risk of a subsequent diagnosis of asthma. Among 1- and 2-year-olds, however, those with wheeze only with colds and those with attacks of shortness of breath with wheeze were more likely to be diagnosed with asthma later when compared with children without those symptoms (odds ration = 2.1; p < 0.05 for wheeze only with colds). At ages 3 to 4 years, symptoms were even more strongly associated with subsequent asthma (odds ratio = 7.2; p < 0.0001 for attacks of shortness of breath with wheeze). CONCLUSION: Although respiratory symptoms reported by parents very early in life are not significantly associated with future asthma, those symptoms that begin at or persist through ages 3 to 4 years are.

Adolescent↗
PubMed1995

The natural history of insomnia and its relationship to respiratory symptoms.

BACKGROUND: Although insomnia is a frequent complaint among patients, epidemiologic study has been limited. Researchers have reported a wide range in the prevalence of this complaint in a variety of selected populations. Other parameters, such as incidence and remission rates, have not been reported. METHODS: Subjects of the Tucson (Ariz) Epidemiologic Study of Obstructive Lung Disease were asked questions about trouble sleeping in the 1984-1985 (survey I) and 1990-1992 (survey II) surveys. Answers were analyzed along with responses to questions about age, sex, respiratory symptoms, and drug and alcohol use for sleep. RESULTS: The prevalence of insomnia was similar in both surveys, 34.4% in survey I and 34.1% in survey II. Women had a higher prevalence of insomnia than men in both surveys, and insomnia was more common among older subjects (50.6% of the women aged 65 years or older had insomnia in survey II). In addition, the incidence of new insomnia in survey II was higher in the same groups. Grouping subjects by respiratory symptoms, we found that the prevalence of insomnia was significantly related to cough, dyspnea, or wheeze. Furthermore, subjects with persistent or new respiratory symptoms at survey II were less likely to have remission of insomnia by that survey (31.6% vs 51.5%; P < .05; odds ratio, 0.43) and more likely to develop new insomnia (28.6% vs 14.5%; P < 05; odds ratio, 2.36) than subjects with either no symptoms or disappearance of their symptoms by survey II. CONCLUSIONS: In our population, insomnia is a common dynamic complaint whose frequency waxes and wanes in association with respiratory symptoms.

Adult↗
PubMed1995

The relationship between parental and children's serum IgE and asthma.

This paper examines the familial aggregation of physician-diagnosed asthma in relation to the age- and sex-standardized total serum IgE levels of children and their parents in a sample of the general population in Tucson, Arizona, that has been followed in a longitudinal study for over 20 yr. There were 591 nuclear families containing 1,177 children who provided information about the presence or absence of a physician diagnosis of asthma. The serum IgE data were less complete: both parents and one or more of their children in 251 of the nuclear families, containing 468 children, had serum IgE levels measured. There was a very strong tendency for asthmatic patients to have asthmatic children, but only a small part of this appeared to be related to the familial aggregation of total serum IgE. In the absence of an asthmatic parent, there was a slight but significantly higher prevalence of asthma in children of whom both parents had IgE levels in the highest tertile. Very high rates of children's asthma depended on there being an asthmatic parent who also had at least moderate levels of serum IgE. It was also shown that asthmatic children have considerably higher total IgE levels than would be expected on the basis of their parents' IgE levels alone. The data appear compatible with several familial-aggregation hypotheses and a strong environmental influence determining which children are likely to develop asthma. We speculate that the inflammation in the airways of asthmatic patients itself tends to increase the serum IgE level, possibly secondary to mediators that it generates.

Adolescent↗
PubMed1995

Incidence and remission of habitual snoring over a 5- to 6-year period.

Habitual snoring is associated with an increased prevalence of hypertension, stroke, and ischemic heart disease. To determine factors that influence the incidence and remission of habitual snoring, we analyzed responses to successive self-administered questionnaires with questions pertaining to snoring in a group of subjects participating in the Tucson Epidemiologic Study of Obstructive Airways Disease. In this study, 1,476 subjects were surveyed 5.8 +/- 0.6 (SD) years apart. Among subjects who habitually snored on the initial survey, 58.2% snored persistently and 35.5% remitted on the ensuing survey. Among subjects who did not habitually snore in the initial survey, 10.5% developed it on the subsequent survey. In further analyses, we found that male sex, obesity, and respiratory symptoms were significant independent risk factors for development of habitual snoring. Age over 65 years, the absence of obesity, and the absence of respiratory symptoms were associated with remission of habitual snoring.

Adult↗
PubMed1994

Findings before the diagnosis of asthma in young adults.

BACKGROUND: Asthma is a poorly understood disease. Risk factors are not established, and the natural history of the disease is unknown. OBJECTIVE: Using subjects of a community-based study, we have prospectively compared young adults destined to develop asthma with control subjects to determine differences between them before diagnosis. METHODS: Subjects were participants of the Tucson Epidemiologic Study of Airways Obstructive Disease. They were studied between the ages of 15 and 19 and subsequently every 1 to 2 years until they were at least 21 years old with questionnaire, spirometry, allergy skin testing, and serum IgE testing. RESULTS: Logistic regression showed that "wheeze" and "attacks of shortness of breath with wheeze" were independently predictive of asthma. Positive allergy skin test results occurred more frequently among subjects who later received a diagnosis of asthma, and initially these subjects had higher serum IgE levels than control subjects (geometric mean IgE = 173.8 IU/ml vs 52.5 IU/ml for control subjects; p < 0.005). Although initial spirometric testing did not distinguish between future asthmatic subjects and control subjects, repeat testing after diagnosis did show significant differences in flows at low lung volumes. CONCLUSIONS: These data suggest that symptoms and findings suggestive of asthma may be present for many years before diagnosis.

Adult↗
PubMed1994

Determinants of percent predicted FEV1 in current asthmatic subjects.

We analyzed the determinants of the percent predicted FEV1 of a large group of diagnosed asthmatic subjects in the Tucson Study of Airway Obstructive Diseases. The 261 subjects were 6 to 88 years old, and 150 (57.5 percent) were female. Although 29.1 percent of the subjects were current smokers and 24.1 percent were ex-smokers, we found that pack-years of smoking was not related to lung function. In addition, age of onset of disease, duration of asthma, eosinophil count, serum IgE level, and allergy skin test reactivity status did not influence the %FEV1. We did find that both severity of wheezing and age of the subject related significantly to %FEV1, and an interaction term of these two variables replaced wheeze and age in the multiple regression equation. Current physician-diagnosed chronic bronchitis and the reported severity of exertional dyspnea also related to %FEV1.

Adult↗
PubMed1993

Antecedent features of children in whom asthma develops during the second decade of life.

In this report we compare 36 subjects in whom asthma was first diagnosed between the ages of 10 and 20 with 297 control subjects. All subjects were studied at age 5 to 9. Among the subjects who acquired a new diagnosis of asthma (NDA), the diagnosis was usually preceded by lower respiratory tract symptoms (31 of the 36 subjects had respiratory symptoms or a diagnosis of rhinitis or chronic bronchitis before asthma developed). Among those tested, more of those with NDA had positive allergy skin test results (56.5%) before diagnosis than control subjects (29.6%; p < 0.05), and the subjects with NDA had higher levels of serum IgE than control subjects (mean log serum IgE = 2.27 in subjects with NDA, 1.76 in control subjects; p < 0.05). Pulmonary function tests revealed no significant differences in the groups before diagnosis. Using logistic regression, we determined that wheezing, cough, a diagnosis of chronic bronchitis, and a positive allergy skin test result were independent risk factors for asthma. When combinations of variables were used, subjects with wheezing and a positive allergy skin test result, cough and a positive test result, and also those with a prior diagnosis of chronic bronchitis alone were at highest risk of a subsequent diagnosis of asthma.

Adult↗
PubMed1991

Findings before diagnoses of asthma among the elderly in a longitudinal study of a general population sample.

Forty elderly subjects who denied ever having asthma or emphysema on enrollment in a longitudinal epidemiologic study later reported consulting a doctor for asthma when they were older than 60 years of age. The average age at which the diagnosis was reported was 70.8 years, after a mean follow-up of 8.5 years. Findings on enrollment in the newly diagnosed subjects with asthma are compared with findings in the 1145 subjects who provided follow-up information when they were older than age 60 years but had never developed asthma. At the time of enrollment, most subjects later diagnosed as having asthma already had wheezing symptoms, suggesting at least a mild asthmatic state, and many subjects had impaired ventilatory function, a positive allergy skin test (especially in association with rhinitis), and blood eosinophilia. Thirty-five percent of the subjects recalled "respiratory trouble before age 16" despite denying prior asthma. The likelihood of a new asthma label was very closely related to the age-sex-standardized serum-IgE level before diagnosis. Newly diagnosed subjects with asthma demonstrated much greater rates of decline in FEV1 than control subjects or than subjects who already had known asthma on enrollment. We conclude that (1) symptoms suggesting asthma are usually present for many years before the diagnosis of the disease in elderly subjects, (2) the serum-IgE level is closely related to the likelihood of a subsequent asthma diagnosis, even in this age group, and (3) a rapid fall in lung function often occurs around the time of initial diagnosis.

Age Factors↗
PubMed1991

Characteristics of asthma among elderly adults in a sample of the general population.

This article describes the characteristics and course of asthma among subjects who were older than 65 years at the time of enrollment in a longitudinal study of a general population sample. It was present in 3.8 percent of men and 7.1 percent of women. An additional 4.1 percent of men reported having "asthma," but they also had seen a physician for "emphysema" and had smoked significantly; their "asthma" diagnosis is regarded as highly questionable. They did not show the elevated rate of allergy skin test reactivity of high serum IgE levels that were characteristic of other asthmatics. Many of the elderly asthmatics (mean age, 72 years) had severe disease with marked ventilatory impairment. There was a close relationship between the severity of wheezing complaints and impairment of the FEV1. Of the 46 patients, 48 percent reported an onset before age 40 years. There was no relationship between severity and age of onset or duration of disease. A second diagnosis of "chronic bronchitis" was reported by 46 percent of the asthmatics, but this did not delineate a distinctive group with late-onset, smoking-related disease. Death rates in the asthmatics tended to be higher than in nonasthmatics (odds ratio, 1.9; CI, 0.998 to 3.70, after stratifying by sex). Over a mean follow-up of 7.44 years, most symptoms as well as the FEV1 remained relatively stable. Chronic productive cough did tend to remit (p less than 0.01), but this was noted in the nonasthmatics as well. We estimate that no more than 19 percent of the asthmatics went into complete remission during follow-up. Most of these had mild initial symptoms; there were no remissions in subjects with severe disease at the time of entry. We concluded that asthma in the elderly is not a rare disease and may be associated with severe symptoms and chronic airways obstruction. If severe, it rarely goes into complete remission but tends to remain a severe, disabling disorder.

Aged↗
PubMed1990

Problems in defining normal limits for serum IgE.

Recommended "normal limits" for serum IgE generally assume that a single upper limit of normal can be applied to all adults. The present article describes the distribution of IgE levels in 2657 subjects in a general population sample in Tucson, Ariz. Limits of IgE defining the lower 5%, 10%, 25%, 50%, 75%, 90%, and 95% in 1569 subjects with negative allergy skin tests and without current asthma, considered a reference group, are provided by age and sex. These cutoffs are then used to compare groups with asthma and with positive allergy skin tests with the reference population. Distributions of IgE levels in these groups are vastly different, but defining an upper "limit of normal" for serum IgE is of doubtful clinical value because there is no single level of IgE that distinguishes different groups with any precision. The spread of IgE values is extremely wide in subjects with and without known allergic diseases.

Adolescent↗
PubMed1989

Association of asthma with serum IgE levels and skin-test reactivity to allergens.

We investigated the association of self-reported asthma or allergic rhinitis with serum IgE levels and skin-test reactivity to allergens in 2657 subjects in a general-population study. Regardless of the subjects' status with respect to atopy or their age group, the prevalence of asthma was closely related to the serum IgE level standardized for age and sex (P less than 0.0001), and no asthma was present in the 177 subjects with the lowest IgE levels for their age and sex (greater than 1.46 SD below the mean). The log odds ratio increased linearly with the serum IgE level after we controlled for possible confounders and the degree of reactivity to skin tests. In contrast, allergic rhinitis appeared to be associated primarily with skin-test reactions to common aeroallergens, independently of the serum IgE level. We conclude that asthma is almost always associated with some type of IgE-related reaction and therefore has an allergic basis, although not all the allergic stimuli that cause asthma appear to have been included in the battery of common aeroallergens we used to assess atopic status. These findings challenge the concept that there are basic differences between so-called allergic ("extrinsic") and nonallergic ("intrinsic") forms of asthma.

Adolescent↗
PubMed1989

Timing of growth inhibition following shoot inversion in Pharbitis nil.

Shoot inversion in Pharbitis nil results in the enhancement of ethylene production and in the inhibition of elongation in the growth zone of the inverted shoot. The initial increase in ethylene production previously was detected within 2 to 2.75 hours after inversion. In the present study, the initial inhibition of shoot elongation was detected within 1.5 to 4 hours with a weighted mean of 2.4 hours. Ethylene treatment of upright shoots inhibited elongation in 1.5 hours. A cause and effect relationship between shoot inversion-enhanced ethylene production and inhibition of elongation cannot be excluded.

Ethylenes↗
PubMed1989

Decline of height with age in adults in a general population sample: estimating maximum height and distinguishing birth cohort effects from actual loss of stature with aging.

The decline in stature with age among adults is well documented. Although part of this represents a birth cohort effect, actual height declines among older individuals are known to contribute to the effect. In this study we used longitudinal changes in the heights of adults in a general population sample to determine the rate of decline in height over time in individuals of different ages. This allowed an estimation of the age at which decline in height begins, a value close to age 40 in both sexes. It also allowed derivation of equations from which the maximum height of subjects can be estimated on the basis of their sex, current height, and age. These equations should prove useful when examining the effect of aging per se on physiological measurements that are height dependent. The data also allow one to compare the magnitude of the effect of year of birth with that of the actual decline in height seen among the elderly. We estimate that approximately 60% of the smaller stature of older male subjects and 45% of the smaller stature of older female subjects is a birth cohort effect deriving from the secular trend toward greater stature; the remainder is a result of an actual decrement in height after the age of 40.

Adult↗
PubMed1988

A reexamination of risk factors for ventilatory impairment.

Previous cross-sectional analyses of data from the Tucson Epidemiological Study of Airways Obstructive Diseases have shown significant relationships of ventilatory impairment to a variety of risk factors, including smoking, chronic productive cough, a history of childhood respiratory illnesses, atopy, blood eosinophilia, and serum immunoglobulin E (IgE). In the present report, we reexamine these relationships in subjects 40 to 74 yr of age to determine the effect of excluding known asthmatics who, as a group, have markedly impaired lung function. After exclusion of asthmatics, atopy, eosinophilia, and IgE no longer appear to be significant risk factors for ventilatory impairment, and nonasthmatic nonsmokers show almost no remaining ventilatory impairment. In current smokers, quantitative relationships of FEV1 to pack-years of cigarette consumption and to chronic productive cough are changed little by excluding asthmatics. In nonasthmatic ex-smokers, however, age at quitting smoking adds significantly to prediction of FEV1 after accounting for pack-years. Young ex-smokers closely resemble nonsmokers, but they become increasingly similar to current smokers as their age at quitting increases. A history of respiratory trouble before 16 yr of age continues to appear to increase susceptibility to smoking effects, even after exclusion of asthmatics. But, as in previous studies, the possible bias of preferential recall of childhood illnesses by impaired subjects limits interpretations of this observation. On the other hand, present findings suggest that such factors as atopy, eosinophilia, and elevated serum IgE may well be risk factors for persistent asthma, but they have no relationship to nonasthmatic forms of chronic obstructive pulmonary disease (COPD).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Effects of shoot inversion on stem structure in Pharbitis nil.

The effects of shoot inversion on stem structure over 72 hr were investigated in Pharbitis nil by analyzing cell number, cell length, and the cross sectional areas of cells, tissues, and regions. An increase in stem diameter can be attributed to an increase in both cell number and cross sectional area of pith (primarily) and vascular tissue (secondarily). Qualitative observations of cell wall thickness in the light microscope did not reveal any significant effects of shoot inversion on this parameter. The inhibition of shoot elongation was accompanied by a significant decrease in cell length in the pith. The results are generally consistent with an ethylene effect on cell dimensions, especially in the pith.

Cell Division↗