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  • 1
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract When diffusion of a vapour in a gaseous medium occurs, any particles suspended in this gaseous mixture will move along the vapour pressure gradient because of the force exerted on them by the diffusing vapour molecules. This effect was first demonstrated by Facy (1) for particulate matter near growing and evaporating water drops. In this paper, quantitative measurements of the velocity, imposed on radioactively marked sub-micron particles (0.03 to 0.1 μ radius), in controlled gradients of water vapour pressure are described. The particle velocity is shown to be a linear function of the vapour pressure gradient over the range measured, such that: (1) $$V_p = 2 \times 10^{ - 4} \frac{{dh}}{{dx}}$$ whereV p is the velocity imposed on the particles (cm/sec), dh/dx is the water vapour pressure gradient (mb/cm). The efficiency for this mechanism in the capturing of the atmospheric aerosol by condensing droplets is considered in the light of these measurements. It is concluded that the fraction of submicron particles, captured by growing droplets in a cloud is generally low. For instance, 100 water droplets per cc growing to 10 μ radius would capture about 5×10−4 of the particulate matter in the surrounding air. Direct experimental verification of this conclusion is presented. In a cloud chamber, droplets were grown up to about 10 μ radius on salt nuclei in an atmosphere containing about 5,000 submicron particles per cc. The particles, were again marked radioactively, and autoradiographic techniques, capable of detecting one marked particle, were used on samples of the droplets obtained by cascade impactor. The autoradiographs showed that the fraction of the particles captured during the growth of the droplets was less than 10−3 per 100 droplets per cc.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Key words Non-insulin-dependent diabetes mellitus ; impaired glucose tolerance ; hypertriglyceridaemia ; hyperinsulinaemia ; non-esterified fatty acid.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although plasma insulin and triglyceride concentrations are positively correlated in many studies, the relationships between insulin resistance, insulin secretion and hypertriglyceridaemia remain unclear. To study these associations, subjects between the ages of 40 and 64 were randomly selected from a general practice register and invited to attend for a standard oral glucose tolerance test for measurement of insulin, triglyceride and non-esterified fatty acid concentrations. The study comprised 1122 subjects who were not previously known to have diabetes and who completed the test. Using the World Health Organisation criteria, 51 subjects were classified to have non-insulin-dependent diabetes mellitus, 188 had impaired glucose tolerance and 883 subjects had normal glucose tolerance. Triglyceride concentrations in subjects with glucose intolerance were elevated compared to those in control subjects, even after adjustment for age, obesity and gender (p 〈 0.001 for subjects with diabetes and p 〈 0.01 for those with impaired glucose tolerance compared to normal subjects). In separate multiple regression analyses for males and females, the most important determinants of the plasma triglyceride concentration were the area under the non-esterified fatty acid suppression curve (p 〈 0.001 in both genders) and the waist-hip ratio (p 〈 0.001 for men and 〈 0.01 for women). The fasting insulin concentration was independently associated with triglyceride concentration in women only (p 〈 0.01). The most important determinant of the area under the non-esterified fatty acid suppression curve in men was the 30-min insulin increment, a measure of insulin secretion, (p 〈 0.001) whereas for women age (p 〈 0.001) and the body mass index (p 〈 0.01) were the most important. [Diabetologia (1994) 37: 889–896]
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 35 (1992), S. 1170-1172 
    ISSN: 1432-0428
    Keywords: Myotonic dystrophy ; proinsulin ; insulin resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Hyperinsulinaemia is a reported feature of the inherited multisystem disorder myotonic dystrophy. This phenomenon has been attributed to a compensatory beta cell response to tissue insulin resistance. In this study, circulating concentrations of insulin, proinsulin, and split proinsulin molecules were determined after an overnight fast in ten patients with myotonic dystrophy using two-site monoclonal antibody-based immunoradiometric assays. Results were compared with ten healthy control subjects matched for age, gender, and body mass index. Oral glucose tolerance (75 g), as defined by World Health Organization criteria, was normal in all subjects. Fasting plasma immunoreactive insulin concentration, as determined using a conventional radioimmunoassay, was almost three times higher (p〈0.005) in the myotonic dystrophy patients than the healthy control subjects. By contrast, fasting concentrations (mean±SEM) of C-peptide (0.75±0.09 vs 0.52±0.03 nmol/l, p=0.07) and immunoradiometrically-determined insulin (60±12 vs 38±4 pmol/l, p=0.09) were not significantly different between the groups. Fasting concentrations of proinsulin (10.3±2.9 vs 1.6±0.3 pmol/l, p〈0.01), and 32–33 split proinsulin (7.8±2.5 vs 2.9±0.4 pmol/l, p〈0.05) were significantly elevated in the patients with myotonic dystrophy. Accordingly, the mean fasting proinsulin∶insulin ratio, expressed as a percentage, was significantly increased in the myotonic patients (20±5 vs 4±1%, p〈0.01). The overall C-peptide response to the oral glucose challenge was significantly greater in the myotonic patients compared with the healthy control subjects (p〈0.001). These results provide corroborative evidence of increased beta-cell secretion in myotonic dystrophy. In addition, myotonic dystrophy is characterised by elevated plasma concentrations of proinsulin-like molecules which may cross-react in insulin radioimmunoassays.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Proinsulin ; split proinsulin ; immunoradiometric assay ; Type 2 (non-insulin-dependent) diabetes mellitus ; impaired Beta-cell function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Plasma insulin, intact proinsulin and 32–33 split proinsulin measured by specific immunoradiometric assays and insulin and C-peptide measured by radioimmunoassay were measured during a constant infusion of glucose test in ten diet-treated subjects with a history of Type 2 (non-insulin-dependent) diabetes (termed diabetic subjects), mean fasting plasma glucose 6.0 ± 1.0 mmol/l (mean ± SD), and 12 non-diabetic control subjects. Immunoreactive insulin concentrations measured by radioimmunoassay were 33 higher than insulin and 16 % higher than the sum of insulin and its precursors by immunoradiometric assay. The diabetic and non-diabetic subjects had similar fasting concentrations of insulin, intact proinsulin and 32–33 split proinsulin. The ratio of fasting intact proinsulin to total insulin was greater in the diabetic than the non-diabetic group 12.0 % (6.8–21.0 %, 1 SD range) and 6.3 % (4.0–9.8 %), respectively,p 〈 0.01), though the groups overlapped substantially. After glucose infusion, diabetic and non-diabetic subjects had similar intact proinsulin concentrations (geometric mean 4.9 and 5.2 pmol/l, respectively), but the diabetic group had impaired insulin secretion by immunoradiometric assay (geometric means 55 and 101 pmol/1,p 〈 0.05) or by radioimmunoassay C-peptide (geometric means 935 and 1410 pmol/1,p 〈 0.05), though not by radioimmunoassay insulin (87 and 144 pmol/1,p = 0.12), respectively. Individual immunoradiometric assay insulin responses to glucose expressed in terms of obesity were subnormal in nine of ten diabetic subjects. Radioimmunoassay insulin and C-peptide gave less complete discrimination ( subnormal responses in six of ten and eight of ten, respectively). Thus, raised proinsulin and proinsulin:total insulin ratio are not necessarily a feature of mild diet-treated Type 2 diabetic patients with subnormal insulin responses to glucose.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; impaired glucose tolerance ; hypertriglyceridaemia ; hyperinsulinaemia ; non-esterified fatty acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although plasma insulin and triglyceride concentrations are positively correlated in many studies, the relationships between insulin resistance, insulin secretion and hypertriglyceridaemia remain unclear. To study these associations, subjects between the ages of 40 and 64 were randomly selected from a general practice register and invited to attend for a standard oral glucose tolerance test for measurement of insulin, triglyceride and non-esterified fatty acid concentrations. The study comprised 1122 subjects who were not previously known to have diabetes and who completed the test. Using the World Health Organisation criteria, 51 subjects were classified to have non-insulin-dependent diabetes mellitus, 188 had impaired glucose tolerance and 883 subjects had normal glucose tolerance. Triglyceride concentrations in subjects with glucose intolerance were elevated compared to those in control subjects, even after adjustment for age, obesity and gender (p〈0.001 for subjects with diabetes and p〈0.01 for those with impaired glucose tolerance compared to normal subjects). In separate multiple regression analyses for males and females, the most important determinants of the plasma triglyceride concentration were the area under the non-esterified fatty acid suppression curve (p〈0.001 in both genders) and the waist-hip ratio (p〈0.001 for men and 〈0.01 for women). The fasting insulin concentration was independently associated with triglyceride concentration in women only (p〈0.01). The most important determinant of the area under the non-esterified fatty acid suppression curve in men was the 30-min insulin increment, a measure of insulin secretion, (p〈0.001) whereas for women age (p〈0.001) and the body mass index (p〈0.01) were the most important.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 59 (1952), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 60 (1953), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 60 (1953), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 60 (1953), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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