| 1. |
- Johannsson, Gudmundur, 1960, et al.
(författare)
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Growth hormone and the acquisition of bone mass.
- 1997
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Ingår i: Hormone research. - 0301-0163. ; 48 Suppl 5, s. 72-7
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Forskningsöversikt (refereegranskat)abstract
- Bone remodelling is a continuous, closely coupled process of bone resorption followed by bone formation. This process is regulated by factors and hormones which include GH, IGF-I and gonadal steroids. GH deficiency in childhood results in short stature and delayed bone maturation and a reduced peak bone mass might account for reduced BMC and BMD. Possible pathophysiological mechanisms for reduced bone mass in both childhood- and adult-onset GH deficiency are discussed. GH treatment effects on bone metabolism include increased remodelling, with increases in BMC, BMD and bone area. Increases in BMC and BMD are delayed while these changes are incorporated into the skeleton. BMC increases to a greater extent than BMD. At a cellular level, GH and IGF-I have direct and indirect effects on osteoblast and osteoclast precursors and fully differentiated cells. Osteoblasts possess both oestrogen and androgen receptors and bone loss accelerates with the loss of gonadal function. There are gender differences in GH effects on bone. BMD is related to fracture risk in the hip and lumbar spine in women. GH treatment might decrease fracture risk at a level comparable to oestrogen or bisphosphonate treatment. Patients with the lowest BMD prior to treatment derive the greatest benefit from GH therapy.
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| 2. |
- Boguszewski, C L, et al.
(författare)
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Circulating non-22-kilodalton growth hormone isoforms in acromegalic men before and after transsphenoidal surgery.
- 1997
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 82:5, s. 1516-21
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Tidskriftsartikel (refereegranskat)abstract
- GH represents several molecular isoforms in addition to the main 22-kDa (22K) GH. There have been reports suggesting that circulating non-22K GH isoforms are increased in acromegaly, but the possible implications of such observations in the management of the disease have not been addressed. The aim of this study was to evaluate the proportion of circulating non-22K GH isoforms in acromegaly. In addition, the relationships between the amount of non-22K GH and tumor size, biochemical measurements, and body composition also were investigated. Samples with different GH levels were selected from 24-h GH profiles from 15 acromegalic men evaluated before and 1 yr after transsphenoidal surgery and from 13 healthy men. The serum non-22K GH levels, expressed as percentage of total GH concentration, were determined by the 22K GH exclusion assay, which is based on immunomagnetic extraction of 22K GH from serum and quantitation of non-22K GH using a polyclonal GH assay. The proportion of non-22K GH isoforms was fairly constant in different samples from the same patient, regardless of the GH level. However, a wide variation of values was observed among acromegalics, both before (14-51%) and after surgery (8-62%). The proportion of non-22K GH isoforms was increased in untreated patients, compared with controls (26.6 vs. 17.4%; P < 0.01), and the values correlated significantly to tumor size, mean 24-h GH concentration, serum PRL, and extracellular water. After surgery, patients not truly cured, with mean 24-h GH concentration of 1 microg/L or more, had an increased proportion of non-22K GH, compared with those with levels less than 1 microg/L (P < 0.01). In the former group, the median values were similar than those in untreated acromegalics (34 vs. 26.6%, respectively), whereas in the latter, they were comparable with those in the controls (15.2 vs. 17.4%, respectively). We conclude that acromegalics have an increased proportion of circulating non-22K GH isoforms. The values are fairly constant in different samples from an individual, regardless of GH level, but a large spectrum can be observed among patients. This variability suggests that different pituitary adenomas secrete GH isoforms in variable amounts. Our observation that a higher proportion of non-22K GH isoforms is present in patients not truly cured after surgery suggests that the evaluation of non-22K GH isoforms can be useful in the follow-up of acromegalic patients.
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| 3. |
- Svensson, J, et al.
(författare)
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Insulin-like growth factor-I in growth hormone-deficient adults: relationship to population-based normal values, body composition and insulin tolerance test.
- 1997
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Ingår i: Clinical endocrinology. - 0300-0664. ; 46:5, s. 579-86
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Tidskriftsartikel (refereegranskat)abstract
- Although an insulin tolerance test (ITT) is the most commonly used method for detecting growth hormone (GH) deficiency (GHD) in adults, measurements of serum insulin-like growth factor-I (IGF-I) may also be of value.To validate the use of serum IGF-I concentration in the diagnosis of GHD in adults.A cross-sectional study.One hundred and four patients, 60 men and 44 women, with known pituitary disease and verified GHD based on ITT.Serum IGF-I was determined by radioimmunoassay after acid-ethanol extraction. Body composition was estimated with total body potassium combined with total body water assessments.According to age- and sex-adjusted population-based references values, 51 patients had serum IGF-I concentrations below -2 SD of the predicted values and 53 had concentrations within 2 SD. Fifty-seven per cent of the patients aged 41 years (25th percentile) or below and 39% of the patients aged 57 years (75th percentile) or above had serum IGF-I concentrations below -2 SD. Women had lower mean IGF-I SD scores than men (P < 0.01). Serum IGF-I was correlated with peak GH response during ITT (r = 0.40; P < 0.001), age (r = -0.27; P < 0.01), duration of hypopituitarism (r = -0.52; P < 0.001), number of pituitary hormonal deficiencies (r = -0.35; P < 0.001), body cell mass (r = 0.30; P < 0.01) and serum insulin (r = 0.21; P < 0.05). The peak GH response during ITT correlated with spontaneous GH secretion, duration (P = -0.48; P < 0.001) and number of deficiencies (r = -0.50; P 0.001).The measurement of serum IGF-I concentrations is not suitable as a single diagnostic test for growth hormone deficiency in adults. Even as a screening test, its use appears to be limited, especially in elderly subjects. The serum level of IGF-I was influenced by several factors in addition to GH, such as age, gender, anthropodometry and serum insulin level. The peak GH response during the insulin tolerance test appears to be influenced to a lesser degree by these factors.
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| 4. |
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| 5. |
- Johannsson, Gudmundur, 1960, et al.
(författare)
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Growth hormone treatment of abdominally obese men reduces abdominal fat mass, improves glucose and lipoprotein metabolism, and reduces diastolic blood pressure.
- 1997
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 0021-972X. ; 82:3, s. 727-34
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Tidskriftsartikel (refereegranskat)abstract
- The most central findings in both GH deficiency in adults and the metabolic syndrome are abdominal/visceral obesity and insulin resistance. Abdominal obesity is associated with blunted GH secretion and low serum insulin-like growth factor-I concentrations. GH treatment in GH-deficient adults has demonstrated favorable effects on most of the features of GH deficiency in adults, but it is not known whether GH can improve some of the metabolic aberrations observed in abdominal/visceral obesity. Thirty men, 48-66 yr old, with abdominal/visceral obesity were treated with recombinant human GH (rhGH) in a 9-month randomized, double-blind, placebo-controlled trial. The daily dose of rhGH was 9.5 micrograms/kg. Body fat was assessed from total body potassium, and abdominal sc and visceral adipose tissue was measured using computed tomography. The glucose disposal rate (GDR) was measured during an euglycemic, hyperinsulinemic glucose clamp. In response to the rhGH treatment, total body fat and abdominal sc and visceral adipose tissue decreased by 9.2 +/- 2.4%, 6.1 +/- 3.2%, and 18.1 +/- 7.6%, respectively. After an initial decrease in the GDR at 6 weeks, the GDR increased in the rhGH-treated group as compared with the placebo-treated one (P < 0.05). The mean serum concentrations of total cholesterol (P < 0.01) and triglyceride (P < 0.05) decreased, whereas blood glucose and serum insulin concentrations were unaffected by the rhGH treatment. Furthermore, diastolic blood pressure decreased and systolic blood pressure was unchanged in response to rhGH treatment. This trial has demonstrated that GH can favorably affect some of the multiple perturbations associated with abdominal/visceral obesity. This includes a reduction in abdominal/visceral obesity, an improved insulin sensitivity, and favorable effects on lipoprotein metabolism and diastolic blood pressure.
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| 6. |
- Johannsson, Gudmundur, 1960, et al.
(författare)
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Individualized dose titration of growth hormone (GH) during GH replacement in hypopituitary adults.
- 1997
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Ingår i: Clinical endocrinology. - 0300-0664. ; 47:5, s. 571-81
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Tidskriftsartikel (refereegranskat)abstract
- Until now, GH treatment in GH-deficient adults has employed dose schedules of GH based on body weight or body surface area and has ignored individual responsiveness to GH. This trial has studied the effects of an individualized GH dose adjusted to match a combination of clinical response, normalization of serum IGF-I concentration and body composition.Two closely-matched groups, each comprising 30 GH-deficient adults, 38 men and 22 women aged 48 years, were treated with GH for 12 months. The high dose (HD) group received a target dose of 12 micrograms/kg per day and the individualized dose (ID) group received an initial daily GH dose of 0.17 or 0.33 mg per day (0.5 and 1 IU, respectively), independent of body weight, with dose adjustments thereafter.Serum concentrations of IGF-I, lipoprotein(a), insulin, calcium, intact PTH, osteocalcin and blood glucose were measured. Body composition was determined according to a 4-compartment model using total body potassium and tritiated water as input variables. Total body nitrogen was measured by in vivo neutron activation and total body bone mineral content by dual energy X-ray absorptiometry.At 12 months, the daily dose of GH was 0.55 +/- 0.03 mg and 0.45 +/- 0.03 mg in the HD and ID groups, respectively (P < 0.05). In the HD group, the mean serum IGF-I increased to levels well above the predicted level, while in the ID group the mean serum IGF-I normalized. Side-effects were experienced by 70% of the subjects in the HD group and by 30% in the ID group (P < 0.001). A similar response to GH in terms of body composition, glucose homeostasis, lipoprotein(a) and blood pressure was obtained in both treatment groups. However, the treatment response in terms of serum calcium, intact PTH and osteocalcin was more marked in the HD group.Similar efficacy, with a lower dose of GH and fewer side-effects, was obtained by considering individual responsiveness to GH as compared to higher doses of GH adjusted to match body weight.
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| 7. |
- Johannsson, Gudmundur, 1960, et al.
(författare)
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Two years of growth hormone (GH) treatment increase isometric and isokinetic muscle strength in GH-deficient adults.
- 1997
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 82:9, s. 2877-84
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Tidskriftsartikel (refereegranskat)abstract
- GH deficiency in adults is associated with reduced muscle mass and muscle strength. The objective of this trial was to follow the effect of 2 yr of GH treatment in GH-deficient adults on muscle performance in relation to a reference population. Knee extensor and flexor strengths for isometric and isokinetic concentric muscle strength were measured using a Kin-Com dynamometer. Hand-grip strength was measured in both hands. The fatigue index was calculated as the percent reduction in peak torque at 50 repeated isokinetic knee extensions. Superimposed, single twitch electrical stimulation was performed. The GH-deficient subjects had lower isometric knee extensor, knee flexor, and hand-grip strength than the reference population. Two years of GH treatment increased and normalized the mean isometric knee extensor and flexor strengths. The concentric knee flexor and extensor strength at an angular velocity of pi rad/s increased, as did the concentric knee flexor strength at an angular velocity of pi/3 rad/s. The increase in muscle strength was more marked in younger patients and in patients with lower initial muscle strength than predicted. Quadriceps endurance decreased, whereas the effect of superimposing single twitches on isometric contraction and hand-grip strength was unaffected by the GH treatment. Two years of GH therapy in GH-deficient adults increased and normalized isokinetic and isometric muscle strength studied in proximal muscle groups. Hand-grip strength and the degree of lack of maximal motor unit activation on voluntary isometric knee extensor force did not change. The dynamic local muscle fatigue index decreased.
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| 8. |
- Oscarsson, J, et al.
(författare)
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Diurnal variation in serum insulin-like growth factor (IGF)-I and IGF binding protein-3 concentrations during daily subcutaneous injections of recombinant human growth hormone in GH-deficient adults.
- 1997
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Ingår i: Clinical endocrinology. - 0300-0664. ; 46:1, s. 63-8
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Tidskriftsartikel (refereegranskat)abstract
- Whereas there seems to be little, if any, circadian variation in circulating concentrations of IGF-I and IGFBP-3 in healthy subjects, there are conflicting reports on this issue in GH-deficient patients treated with GH as a daily subcutaneous injection. We have therefore investigated the 24-hour serum profiles of IGF-I and IGFBP-3 concentrations after one week and more than one year of GH treatment.Eleven subjects, with adult onset GH deficiency mainly caused by pituitary adenomas were included in the study.In an open study, six subjects (three women and three men; age (+/-SEM) 41.2 +/- 3.9 years) were investigated after one week of GH therapy and five subjects (three women and two men; age (+/-SEM) 61.4 +/- 3.3 years) were investigated after 13-40 months of GH therapy. The GH injections were given at 2000 h. The subjects were hospitalized for 24-hour blood sampling at 1-hour intervals and serum concentrations of GH, IGF-I and IGFBP-3 were determined.There was a significant diurnal variation in serum IGF-I and IGFBP-3 concentrations both in the subjects who had received GH for one week and in those who had received GH treatment for more than one year. The serum concentrations of IGF-I and IGFBP-3 were highest in the morning and lowest during night-time and early morning. The molar IGF-I/IGFBP-3 ratio varied significantly with time in both groups of patients in a similar way as IGF-I and IGFBP-3 indicating a more pronounced variation in IGF-I compared with IGFBP-3 in response to the GH therapy.Significant diurnal variations in serum IGF-I and IGFBP-3 concentrations occur after one week and more than one year of GH treatment with daily subcutaneous injections. The results indicate that the free fraction of IGF-I may exhibit a diurnal variation.
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