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L Fryklund

Publications and source records attributed to L Fryklund.

At least 19 recordsLinked to original sources
PubMed2006

The d3/fl-growth hormone (GH) receptor polymorphism does not influence the effect of GH treatment (66 microg/kg per day) or the spontaneous growth in short non-GH-deficient small-for-gestational-age children: results from a two-year controlled prospective study in 170 Spanish patients.

CONTEXT: The d3/fl-GH receptor (d3/fl-GHR, exon 3-deleted/full-length GHR) has recently been associated with responsiveness to GH therapy. OBJECTIVE: The objective of the study was to evaluate whether the d3/fl-GHR genotypes influence the intensity of spontaneous and/or GH therapy-stimulated growth in small-for-gestational-age (SGA) patients. DESIGN: This was a 2-yr prospective, controlled, randomized trial. SETTING: Thirty Spanish hospitals participated. Auxologic and GH secretion evaluation was hospital based, whereas molecular analyses and auxologic data computation were centralized. PATIENTS: Patients included 170 short SGA children: 140 remained prepubertal and 30 entered puberty during the second follow-up year. INTERVENTION: Eighty-six were treated with GH (66 microg/kg.d) for 2 yr and 84 were not treated. MAIN OUTCOME MEASURES: Previous and 2-yr follow-up auxologic data were recorded at each hospital, d3/fl-GHR genotypes determined, and data analyzed for patients who remained prepubertal (group 1, 68 GH treated and 72 non-GH treated) and for all the patients (group 2). RESULTS: In group 1 GH-treated patients, growth velocity, and height-sd score during the first and second years, total 2-yr height gain (18.5 +/- 2.4 cm in d3/d3; 18.4 +/- 2.6 in d3/fl; 19.5 +/- 2.3 in fl/fl), Delta 2-yr height increase (9.1 +/- 2.4 cm in d3/d3; 9.4 +/- 3.0 in d3/fl; 10.4 +/- 2.1 in fl/fl), first-year growth prediction and studentized residual values (0.08 +/- 1.26 in d3/d3; 0.28 +/- 1.21 in d3/fl; 0.67 +/- 0.95 in fl/fl) did not differ among the d3/fl-GHR genotypes. In group 1 non-GH-treated patients, neither growth velocity nor height-sd score changed significantly, and values were similar in each d3/fl-GHR genotype. Results in all patients (group 2) were similar to those in group 1. CONCLUSIONS: In short non-GH-deficient SGA children, both spontaneous growth rate and responsiveness to 66 microg/k.d GH therapy were similar for each d3/fl-GHR genotype carried.

Body Height↗
PubMed2004

Pharmacokinetics and metabolism of tesaglitazar, a novel dual-acting peroxisome proliferator-activated receptor alpha/gamma agonist, after a single oral and intravenous dose in humans.

The pharmacokinetics of tesaglitazar (GALIDA), a novel dual-acting peroxisome proliferator-activated receptor alpha and gamma agonist, were studied in eight healthy male subjects. The subjects initially received either a single oral or intravenous (i.v.) dose of 1 mg of [(14)C]tesaglitazar. After a washout period, they received 1 mg of nonlabeled tesaglitazar via the alternative administration route. Serial blood samples and complete urine and feces were collected until 336 h postdose. Tesaglitazar absorption was rapid, with maximum plasma concentration (C(max)) at approximately 1 h postdose, and the absolute bioavailability was approximately 100%, suggesting no, or negligible, first-pass metabolism. Mean plasma clearance was 0.16 l/h and the volume of distribution at steady state was 9.1 liters. After either route of administration, the plasma concentration-time profiles of radioactivity and tesaglitazar were virtually identical, indicating low systemic metabolite concentrations and formation rate limitation of metabolite elimination. The elimination half-life of radioactivity and tesaglitazar was approximately 45 h. Radioactivity recovery was complete in all subjects, with mean values of 99.9% (i.v.) and 99.6% (oral). Tesaglitazar was mainly metabolized before excretion, and most radioactivity (91%) was recovered in urine. Approximately 20% of the dose was recovered unchanged after either administration route, resulting in a renal clearance of 0.030 l/h. Most of the radioactivity in urine was identified as acyl glucuronide of tesaglitazar. Plasma protein binding of tesaglitazar was high ( approximately 99.9%), and the mean blood-plasma partitioning ratio was 0.66, suggesting low affinity for red blood cells. There was no indication of partial inversion of the (S)-enantiomer to the corresponding (R)-form. Tesaglitazar was well tolerated.

Administration, Oral↗
PubMed2003

Growth hormone enhances proinflammatory cytokine production by monocytes in whole blood.

Growth hormone (GH) has been used as anabolic therapy to treat catabolic patients. In a recent study, however, administration of high doses of GH to critically ill adults was associated with an increase in morbidity and mortality. Preponderance of septic shock and uncontrolled infections as causes of death in these patients suggests an immuno-modulatory effect of GH. Our hypothesis was that GH treatment may modulate the production of proinflammatory cytokines, which are implicated in sepsis. In our study, human monocytes in whole blood were activated with lipopolysaccaharide (LPS) (1-100 ng/ml) purified from a clinical isolate of group B Neisseria meningitidis in the presence of a high dose of GH (100 ng/ml). The subsequent proinflammatory cytokine response was analysed by intracellular cytokine staining and flow cytometry. Our results show that GH enhances IL1-alpha, IL-6 and TNF-alpha production by LPS activated monocytes in whole blood. The modulation of cytokines by GH may be responsible for the adverse consequences of GH in critically ill patients.

Adult↗
PubMed2002

The metabolic effects of short-term administration of physiological versus high doses of GH therapy in GH deficient adults.

OBJECTIVE: GH treatment has demonstrated favourable effects on most features of GH deficiency in hypopituitary adults. However, most studies employed supraphysiological GH doses, resulting in deterioration in insulin sensitivity (SI). The short-term metabolic effects of physiological doses of GH therapy in GH deficient (GHD) adults are largely unknown. We therefore compared the effects of short-term administration of two 'physiological' ('lowest' dose: 0.0017 mg/kg/day; 'low' dose: 0.0033 mg/kg/day) with two 'supraphy-siological' ('high' dose: 0.010 mg/kg/day; 'highest' dose: 0.025 mg/kg/day) GH doses on SI, beta-cell function, IGF-1 and IGFBPs -1 and -3 in a group of GHD adults. PATIENTS AND METHODS: Thirteen GHD adults were recruited (seven men, aged 23-63 years). For each of the four doses, six patients (three men) were allocated randomly to undergo a 7-day treatment phase. Fasting blood samples were collected daily (days 1-8), and SI and beta-cell function were calculated using the homeostasis model assessment (HOMA). RESULTS: All four GH doses increased IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio, and decreased IGFBP-1 from day 3 onwards (P < 0.05). The highest dose increased fasting glucose (P < 0.001), insulin (P < 0.001) and beta-cell function (P < 0.001), but decreased SI (P < 0.001). The high and low doses did not modify fasting glucose and insulin, SI or beta-cell function, whereas the lowest dose enhanced beta-cell function (P < 0.05). The overall increase in the GH dose increased IGF-1, IGFBP-3, fasting glucose and insulin (P < 0.001), demonstrated a positive correlation with the final change in fasting glucose (r = 0.5, P < 0.05) and insulin (r = 0.8, P < 0.001) and a negative correlation with final SI (r = -0.5, P < 0.05). CONCLUSIONS: Our results suggest that short-term administration of the highest GH dose induced insulin resistance, whereas the lowest dose (0.0017 mg/kg/day) could represent the optimal starting dose in GHD adults due to its beneficial effects on beta-cell function without compromising SI. It is, however, yet to be determined whether the positive effects of the lowest GH dose on beta-cell function can be demonstrated over a longer period of time.

Adult↗
PubMed1997

Effects of constant infusion with insulin-like growth factor-I (IGF-I) to immature female rats on body weight gain, tissue growth and sexual function. Evidence that such treatment does not affect sexual maturation of fertility.

Plasma levels for insulin-like growth factor-I (IGF-I) steadily increase in female rats between 20 and 40 d of life, and this increase is intimately related to the wellknown growth spurt occurring at this age. Since specific actions of IGF-I related to sexual function have been described at the ovarian and hypothalamic levels, an endocrine role of rising circulating IGF-I levels during sexual maturation cannot be excluded. Therefore, the impact of adult-type plasma IGF-I levels during the juvenile age, on body weight (BW) gain, growth of several organs, sexual development, and fertility has been evaluated. Female Sprague-Dawley rats were infused with rhIGF-I (2 and 4 micrograms/g BW/d, using Alzet minipumps), between 20 and 41 d of life. When infusing 2 micrograms/g BW/d, plasma levels for IGF-I were increased 1.5- to 2-fold over controls at all ages studied. They were further increased with the higher dosage, but only after 35 d of age. Plasma levels for insulin-like growth factor binding protein (IGFBP)-1 to -3 were clearly increased. BW gain was significantly increased, but only with the higher dosage. Tail length was never modified. In contrast, a growth acceleration for spleen, kidneys, adrenals, and ovaries was observed with both dosages. The ovarian weight of treated animals represented approx 140% of control animals with the 4 micrograms/g BW/d dosage. Histology of the enlarged ovaries did not reveal any abnormalities. No meaningful modification of the timing of vaginal opening was observed, and fertility was not comprised by previous rhIGF-I infusion during 20-41 d age period. In summary, early exposure to increased (adult-like) plasma IGF-I levels did not modify BW gain or tail length, but affected the development of spleen, kidneys, adrenals, and ovaries. Exposure to supraphysiological plasma IGF-I levels (> 1200 ng/mL), accelerated BW gain and increased the weight of all organs studied. No signs of precocious sexual maturation were seen and fertility was normal. In conclusion, prematurely increased plasma IGF-I levels affected somatotropic parameters, but not the onset of sexual function.

Animals↗
PubMed1990

Anabolic and tissue repair functions of recombinant insulin-like growth factor I.

Recombinant human insulin-like growth factor I (rhIGF-I) has been produced in yeast and purified using conventional biochemical techniques. It has been shown to have receptor-binding properties and in vitro growth-promoting activities comparable to those of plasma-derived IGF-I. The anabolic actions of IGF-I can be studied using both systemic and local administration in vivo. The growth-promoting activity and systemic anabolic actions of recombinant IGF-I were studied in mutant dwarf rats. IGF-I was infused intravenously for 9 days and resulted in a significant gain in body weight and significant bone growth, though the effects were not as great as those observed with human growth hormone (hGH). IGF-I also had selective effects on specific organs which were not observed in hGH-treated animals. The results indicate that the growth-promoting effects of IGF-I show a different pattern compared to hGH. The effects of local administration of recombinant IGF-I on tissue regeneration and maintenance were also studied in hypophysectomized and normal rats. After hypophysectomy, the regeneration processes were impaired when both peripheral nerve regeneration and incision wound healing were considered. The results indicate that local administration could have significant effects on regeneration of, for example, peripheral nerves.

Animals↗
PubMed1989

Isolation and characterization of a glycosylated form of human insulin-like growth factor I produced in Saccharomyces cerevisiae.

Expression and secretion of human insulin-like growth factor-I (IGF-I) in Saccharomyces cerevisiae was achieved by linking an actin (ACT) promoter to an MF alpha 1 prepro leader peptide/IGF-I gene fusion. Purified human IGF-I from yeast culture media was found to contain, in addition to the native form, also a glycosylated variant. Structural studies showed that both IGF-I forms were processed identically, resulting in 70-amino-acid long polypeptides, with intact N-terminal and C-terminal residues of glycine and alanine, respectively. The glycosylation site was determined to threonine-29 (Thr29), by 1H NMR spectroscopy and protein sequence analysis of an isolated tryptic peptide(22-36). No other glycosylation sites were found. Only mannose was detected in the sugar analysis, with an estimated content of 4.5% w/w corresponding to 2 mannose residues per molecule of IGF-I. The carbohydrate structure, determined by 1H and 13C NMR spectroscopy, was found to be alpha-D-Manp(1----2)alpha-D-Manp(1----3)Thr corresponding to an O-linked glycoprotein structure. No other post-translational modifications could be identified in the glycosylated IGF-I form. Furthermore, this form was highly active, comparable to native IGF-I, exhibiting a specific activity of 20,500 units/mg, as determined by a radio-receptor assay.

Actins↗
PubMed1989

Characterisation of a secreted form of recombinant derived human growth hormone, expressed in Escherichia coli cells.

Recombinant DNA derived human growth hormone (rhGH), Genotropin, has been expressed in E. coli cells as a pre-hormone, where the heat stable enterotoxin II signal peptide (STII) was linked to hGH to get secretion of the hormone to the periplasmatic space. The pre-hormone was efficiently cleaved during secretion, by an endogenous signal peptidase generating the correct N-terminal (Phe) end as shown by protein sequence analysis. The purity of rhGH was studied by SDS-PAGE, in combination with laser densitometry and HI-HPLC. These techniques showed that the level of modified rhGH forms, e.g. aggregated and proteolytically cleaved (16 and 6 kDa) in the preparation was in the 0.5-1% range. Furthermore, evidence that the correct disulphide bonds (Cys53-Cys165; Cys182-Cys189) were formed in rhGH during secretion has been shown by a combination of tryptic fingerprint and amino acid analysis. CD-spectroscopic analysis suggested an identical secondary structure to that of pituitary derived human growth hormone (pit-hGH). Isoelectric focusing revealed an isoelectric point (pI) for rhGH of 5.0 similar to pit-hGH and in excellent agreement with the theoretical value 5.1, based on the primary sequence. Finally, an apparent molecular weight of 22,000 was obtained for rhGH, by SDS-PAGE. All these physico-chemical studies suggest that rhGH is structurally identical to pit-hGH, somatotropin.

Amino Acid Sequence↗
PubMed1989

Growth responses in a mutant dwarf rat to human growth hormone and recombinant human insulin-like growth factor I.

A new mutant GH-deficient dwarf rat has been used to study the effects of iv infusions of human GH (hGH) and recombinant human insulin-like growth factor I (hIGF-I). This animal has only about 5% of normal pituitary GH content, low circulating GH levels, and no regular GH surges. The defect seems to be specific for GH. Infusions of hIGF-I at 180 micrograms/day for 9 days elevated serum IGF-I concentrations significantly over those in the saline-infused controls (713 +/- 20 ng/ml vs. 395 +/- 31 ng/ml); hGH infusions did not raise IGF-I levels significantly (435 +/- 20 ng/ml). Gel filtration of serum samples showed that the high-dose hIGF-I infusions increased free IGF concentrations, without apparently altering the pattern of IGF-I binding whereas hGH infusions increased the amount of high mol wt IGF-I binding protein. Neither IGF-I nor hGH infusions affected the small amounts of rat GH present in the dwarf rat pituitary glands. Continuous iv infusions of hGH (200 mU/day for 9 days) stimulated body wt gain (2.1 +/- 0.2 g/day) and bone growth (96 +/- 9 microns/day) significantly compared to saline-infused dwarf rats (1.2 +/- 0.3 g/day and 43 +/- 3 microns/day). Infusions of hIGF-I at 180 micrograms/day produced a body wt gain (2.1 +/- 0.5 g/day) similar to that seen in the hGH-infused group but a significantly smaller stimulation of bone growth (63 +/- 3 microns/day). Infusion of a 5-fold lower dose of hIGF-I (36 micrograms/day for 9 days) had no effect on body wt or bone growth. Food intake was unaffected by either hGH or hIGF-I infusions. The pattern of tissue growth was affected differentially by hGH and IGF-I infusions that produced the same overall body wt gain. hGH induced a relatively proportional growth in most of the organs studied, whereas hIGF-I infusion at 180 micrograms/day stimulated a disproportionately greater growth of the kidney, adrenals, and spleen. In some of the animals, tissues were extracted for RIA of IGF-I; the amounts of IGF-I in the liver were similar in control, hGH, or IGF-I-infused animals, whereas kidney and adrenals from IGF-I infused animals contained larger amounts of immunoreactive IGF-I than did those tissues from hGH-treated rats. Thus, both hGH and hIGF-I can promote growth in the mutant dwarf rat, but they differ both quantitatively and qualitatively in their pattern of actions.

Animals↗
PubMed1989

A monoclonal antibody to lactogenic receptors from female rat liver.

Affinity-purified lactogenic receptors from female rat liver microsomal membranes were used to raise antibodies in female Balb/c mice. Mouse spleen and myeloma cells were fused and hybridoma-derived monoclonal antibodies (Mabs) were produced by in-vitro cell culture. Mab from a selected clone was sequentially purified by chromatography on a thiophilic gel and on agarose-bound protein A. The Mab was found to be of IgG1 subclass and of kappa type. The Mab recognized membrane-bound and solubilized (by the detergent heptaoxyethylene lauryl ether; G3707) receptors as well as receptors purified by affinity chromatography and subsequent sodium dodecyl sulphate (SDS) electrophoresis from female rat liver. The Mab bound to receptors from several other female rat tissues, such as ovary, kidney and adrenal, whereas there was no binding to liver receptors from cow and rabbit. Displacement experiments showed that the Mab was specific for a lactogenic type of receptor, in agreement with the finding that the Mab did not recognize receptors from male rat liver. The Mab also bound to cytoplasmic receptors (present in the supernatant after centrifugation at 100,000 g) from female rat liver, suggesting a structural similarity between the cytoplasmic and the microsomal receptors. Analysis of purified receptors by SDS electrophoresis and subsequent Western blot with 125I-labelled Mab as a probe showed one band corresponding to an Mr of 45,500 +/- 2500 (n = 5). The same band was obtained with 125I-labelled human GH, showing that the Mab binds to the unit which accommodates the hormone-binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

The acute effects of growth hormone on amino acid transport and protein synthesis are due to its insulin-like action.

GH has acute stimulatory effects on amino acid transport and protein synthesis in a variety of tissues, but it has not been established whether these effects are expressions of the growth-promoting property of GH or of its separate insulin-like action. The 20,000-dalton structural variant of human GH (20K hGH) has been shown to have a high ratio of growth-promoting to insulin-like activity compared to native hGH (22K hGH), suggesting that it could be used as a tool to address the above question. Therefore, experiments were conducted to compare the relative abilities of native 22K hGH and 20K hGH, when added in vitro, to stimulate amino acid transport and protein synthesis in the isolated diaphragm of the female hypophysectomized rat. Paired intact hemidiaphragms were preincubated for 1 h in the absence or presence of various concentrations of 22K or 20K hGH. Then, 3-O-[14C]methylglucose was added to the medium to measure sugar transport as a test of insulin-like activity, and either alpha-[3H]aminoisobutyric acid acid or [3H] phenylalanine was also added to measure amino acid transport or protein synthesis, respectively, during a final hour of incubation. When the responses to the various concentrations of 22K and 20K were compared, 20K hGH was only about 20% as effective as 22K in stimulating 3-O-methylglucose transport, reflecting its markedly attenuated insulin-like activity on the diaphragm. Similarly, 20K hGH was only 20% as effective as 22K hGH in stimulating alpha-aminoisobutyric acid transport and phenylalanine incorporation into protein in the same muscles. Therefore, these findings support the idea that the rapid stimulatory effects of GH on amino acid transport and protein synthesis are expressions of the insulin-like action of GH and are not components of the response of target cells to its growth-promoting action.

3-O-Methylglucose↗
PubMed1987

Biological characterization of purified native 20-kDa human growth hormone.

Because of the propensity of the 20-kDa variant of human growth hormone (GH) to aggregate with itself and with 22-kDa human GH, it has been difficult to prepare monomeric 20-kDa GH in highly purified form. This has been a major complicating factor in determining whether 20-kDa GH has a biological activity profile distinct from that of 22-kDa GH. In the present study, native 20-kDa GH was isolated from a human GH dimer concentrate and purified by a procedure that included column electrophoresis in agarose suspension as a final separation step. This procedure yielded highly purified monomeric 20-kDa GH, which was contaminated to an extent of less than 1% with 22-kDa GH, and which exhibited only a small degree of dimerization upon storage. The native 20-kDa GH was quite active in stimulating growth in hypophysectomized rats, when growth was assessed by body weight gain, longitudinal bone growth, the stimulation of sulfation of cartilage, and the elevation of serum IGF-1 level. However, in all of these growth assays, the 20-kDa GH was somewhat less active than the native 22-kDa GH to which it was compared; e.g., in the body weight gain and longitudinal bone growth assays, it had an estimated potency of 0.6 relative to the 22-kDa GH. The 20-kDa GH exhibited substantial diabetogenic activity when tested for the ability to raise fasting blood glucose concentration and to impair glucose tolerance in ob/ob mice. Also, the native 20-kDa GH had significant in vitro insulin-like activity, although its potency was approximately 20% that of the native 22-kDa GH to which it was compared. Thus, the biological activity profile of native 20-kDa GH differs from that of 22-kDa GH primarily in that insulin-like activity is markedly attenuated.

Animals↗
PubMed1987

Production of authentic recombinant somatropin.

Further developments in recombinant DNA technology, exploiting a natural mechanism for export using a signal peptide in E. coli, have enabled the production of recombinant somatropin, with full biological activity and extremely high purity. The secretion of the protein into the periplasmic space has simplified purification procedures, providing a unique and simple process and a pure and active product.

Base Sequence↗
PubMed1987

Recombinant human insulin-like growth factor: testing the somatomedin hypothesis in hypophysectomized rats.

The in-vivo biological activity of recombinant methionyl insulin-like growth factor I (met-IGF-I) was demonstrated in hypophysectomized rats by following blood glucose after an i.v. bolus injection of met-IGF-I; a dose-dependent decrease in blood sugar was seen. Membrane transport was studied using the non-metabolizable amino acid alpha-aminoisobutyric acid; stimulation was obtained with the highest dose used (90 micrograms/rat). To test the original somatomedin hypothesis, growth studies were performed in hypophysectomized rats. Two or three doses of met-IGF-I were given with three different administration regimes (i.v. or s.c. infusion, or s.c. injections twice daily) for 6 or 8 days. Little growth-promoting activity was observed, with a significant effect on body weight gain obtained only when met-IGF-I was given continuously at the highest dose used (180 micrograms/day). No effect was seen on the in-vivo uptake of radioactive sulphate into cartilage. Epiphyseal cartilage width increased slightly at the highest dose of met-IGF-I, but only when the hormone was given by infusion. When 180 micrograms met-IGF-I/day were given by injections, a significant effect on longitudinal bone growth was obtained (90 micron above control). The levels of IGF in the serum were not measurably increased after s.c. administration of met-IGF-I, whereas after i.v. infusion, significantly raised levels were obtained at the higher dose rates (3.0 +/- 0.3 and 2.8 +/- 0.1 units/ml). Growth hormone was much more effective than met-IGF-I even at 50-fold lower doses. Priming the animals with 10 mu. bovine GH/day followed by combined infusions of GH and met-IGF-I did not reveal any potentiating effects of met-IGF-I in the presence of GH. We conclude that met-IGF-I is a relatively poor growth-promoting agent when given systemically, and that somatomedins are more likely to act as local growth factors rather than as circulating mediators of the growth-promoting effects of GH.

Animals↗
PubMed1986

Current research on recombinant human growth hormone and the related growth factors, IGF-1 and GRF.

A brief introduction is provided to the physiological actions of somatostatin, somatomedins and growth hormone releasing factor (GRF) in relation to human growth hormone (hGH). The development of recombinant DNA techniques allowed the biosynthesis of somatrem (methionyl hGH), and as the methods were refined, authentic recombinant hGH (methionyl-free) has been produced. rhGH is currently undergoing clinical trials in several countries. Recombinant IGF-1 has also been developed by similar methods, utilizing a yeast as the host cell. In contrast, GRF is too small to be biosynthesized, but can be produced by classical peptide synthesis. Only the N-terminal sequence is required for biological activity, and may be 29, 40 or 44 residues long. Research into the biological effects of both IGF-1 and GRF is underway.

Amino Acid Sequence↗