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Biomedical subjects

W Blum

Publications and source records attributed to W Blum.

At least 37 records · Page 2Linked to original sources
PubMed1998

Leptin levels in women with polycystic ovary syndrome before and after treatment with diazoxide.

Leptin, a product of the ob gene, is a 16 kDa protein which is produced by adipocytes. In humans, obesity is a common finding in women with polycystic ovary syndrome (PCOS). The role, however, of leptin in PCOS is not clear. Some studies have reported increased levels of leptin in PCOS, while others report that they are normal. Also, insulin resistance is a common finding in PCOS. The aim of this study was to investigate further the role of insulin in leptin secretion in patients with PCOS by treating them for 10 days with diazoxide, an insulin-reducing compound. Eight women with PCOS, mean age 22.1 +/- 2.7 years, with mean body mass index (BMI) 28.4 +/- 5.7kg/m2, were studied. An oral glucose tolerance test (OGTT) was performed in all women and blood samples were taken before and at 30, 60, 90, 120 and 150 min after the administration of glucose. Glucose, insulin, leptin, free testosterone, delta4 androstenedione, sex hormone binding globulin (SHBG), LH, FSH, IGF-I and insulin-like growth factor-binding protein-3 (IGFBP-3) were measured in the sera taken before the administration of glucose, while glucose and insulin levels were measured in all samples which were collected after the administration of glucose. Diazoxide 300 mg daily was given to all women starting after the end of the OGTT for 10 days. A second OGTT was performed the day after the discontinuation of the diazoxide treatment. The same hormonal and biochemical parameters were also measured in all patients during the second OGTT. After the administration of diazoxide a reduction in sum insulin (262 +/- 147 vs 679 +/- 341 microU/ml. P<().01), leptin (18.5 +/- 10.6 vs 24.2 +/- 10.2 ng/ml, P<0.01), free testosterone (3.0 +/- 1.9 vs 5.1 +/- 1.9 pg/ml, P<0.01), delta4 androstenedione (3.8 +/- 1.9 vs 5.7 +/- 2.0 ng/ml, P<0.01) and IGF-I (219.5 +/- 69.2 vs 314.5 +/- 82.3 ng/ml, P<0.01) levels was observed. Serum SHBG (38.8 +/- 16.8 vs 27.8 +/- 12.1 nmol/l, P<0.01) and sum glucose levels (994.1 +/- 252.7 vs 711.1 +/- 166.1 mg/dl, P<0.05) were increased while IGFBP-3 (3.96 +/- 2.49 vs 3.75 +/- 2.24mg/l), FSH (6.2 +/- 1.8 vs 6.0 +/- 2.5 mU/l) and LH (18.9 +/- 6.7 vs 21.4 +/- 6.7 mU/l) concentrations did not change significantly. A significant positive correlation was found between serum leptin and BMI values before and after administration of diazoxide as well as between leptin, insulin and IGFBP-3 values. Also, sum insulin values correlated significantly with BMI. However, when multiple regression analysis was used this correlation was eliminated except that between leptin and BMI. This was most probably due to the small number of cases. The mechanism of the reduction of leptin levels is unclear. However, it is suggested that the concomitant decrease of insulin levels may play a role.

Adipose Tissue↗
PubMed1996

Characterization of a novel diclofenac metabolite in human urine by capillary gas chromatography-negative chemical ionization mass spectrometry.

A sensitive analytical method was developed to characterize diclofenac metabolites in small amounts of body fluids. Desalted and lyophilized urine samples were extracted with supercritical carbon dioxide directly or after acidic hydrolysis. The extracts were derivatized with N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide. The derivatives were separated by capillary gas chromatography and identified by negative chemical ionization mass spectrometry. Full mass spectra were obtained at a level of 1.10(-9) g/ml. With direct extraction, the metabolites could be analysed in one step as open-chained acids and as (cyclic) oxindoles. By acidic hydrolysis the conjugates were transformed to the oxindoles. With both methods, a new main metabolite, [2-[2,6-dichloro-4-hydroxy-3-methoxyphenyl)amino]phenyl]acetic acid, was identified The mechanism of its formation is discussed.

Acetamides↗
PubMed1996

Immunocytochemical reaction of a haemocyanin antibody in the midgut gland of Nautilus (Cephalopoda, Tetrabranchiata).

The branchial gland of the dibranchiate cephalopods is described as the site of haemocyanin synthesis. Because there is no equivalent to this organ in tetrabranchiate cephalopods the localization of haemocyanin synthesis remained unknown for a long time. In this study we could confirm the conclusions from preliminary investigations concerning the copper content of the midgut gland of Nautilus, which gave the first indications for a possible localization of haemocyanin synthesis in this organ. We developed a polyclonal antibody against Nautilus haemocyanin, tested its specificity, and used it on ultra-thin sections of the tissue of the midgut gland. It could be shown that there is a clear immunogold precipitation only on the triangular basal cells in the terminal alveoli. All the other types of cell in this organ were free of any immunoreactivity. It can be supposed that the triangular basal cells in the terminal alveoli of the midgut gland are the sites of haemocyanin synthesis in Nautilus.

Animals↗
PubMed1996

Critical illness is associated with low circulating concentrations of insulin-like growth factors-I and -II, alterations in insulin-like growth factor binding proteins, and induction of an insulin-like growth factor binding protein 3 protease.

OBJECTIVES: To describe the sequential changes in the circulating concentrations of insulin-like growth factor-I, insulin-like growth factor-II, and insulin-like growth factor binding proteins in critically ill patients. To determine whether critical illness is associated with induction of a specific protease directed against insulin-like growth factor binding protein 3 and to relate these changes to outcome. DESIGN: Prospective, descriptive study. SETTING: Intensive care unit (ICU) of a university hospital. PATIENTS: Eighteen heterogeneous critically ill patients, requiring ventilatory support. INTERVENTIONS: Serial daily blood samples were collected until death or discharge from the ICU. In five patients, samples were also obtained on the ward before discharge from the hospital. MEASUREMENTS AND MAIN RESULTS: Serum concentrations of insulin-like growth factor-I, insulin-like growth factor-II, and insulin-like growth factor binding proteins 1, 2, and 3 were measured by radioimmunoassay. After 5 days, insulin-like growth factor binding protein 3 concentrations were measured on alternate days. Alterations in binding of insulin-like growth factor-I to insulin-like growth factor binding protein 3 and the presence of protease activity directed against insulin-like growth factor binding protein 3 were investigated by Western ligand blotting. Circulating concentrations of insulin-like growth factor-I and insulin-like growth factor-II were low and remained low throughout the 7-day study period. Insulin-like growth factor binding protein 1 concentrations were initially increased to within the fasting range, but subsequently decreased. There was considerable variability in insulin-like growth factor binding protein 2 concentrations, but generally, concentrations were at the upper end of the normal range throughout. Insulin-like growth factor binding protein 3 concentrations were consistently low and Western ligand blotting at the nadir of the insulin-like growth factor-I concentration demonstrated the presence of a protease directed against insulin-like growth factor binding protein 3. The last recorded concentrations of insulin-like growth factor-I and insulin-like growth factor binding protein 3 were higher in survivors than in nonsurvivors (p < .05). Two patients were also studied for a prolonged period. In one patient, a survivor, insulin-like growth factor-I and insulin-like growth factor binding protein 3 were low initially, but later increased in association with recovery and cessation of protease activity over a period of 33 days. In another patient, a nonsurvivor, insulin-like growth factor-I and insulin-like growth factor binding protein 3 remained low and protease activity persisted until the patient died 38 days after admission to the ICU. CONCLUSIONS: Critical illness is associated with low circulating concentrations of insulin-like growth factor-I, insulin-like growth factor-II, and insulin-like growth factor binding protein 3 and these low values are associated with induction of protease activity specifically directed against insulin-like growth factor binding protein 3. In survivors, recovery is associated with increasing insulin-like growth factor-I and insulin-like growth factor binding protein 3 concentrations and cessation of protease activity. The therapeutic effects of exogenous growth factors are likely to be influenced by these changes.

Adolescent↗
PubMed1996

Ibuprofen and diclofenac sodium in the treatment of osteoarthritis: a comparative trial of two once-daily sustained-release NSAID formulations.

An investigator-blind, parallel-group, multicentre study was undertaken to compare the efficacy and tolerability of once-daily, sustained-release (s-r) ibuprofen and diclofenac sodium in patients (mean age 59.8 years) suffering from painful osteoarthritis affecting chiefly the knee and/or hip. Patients attending eight Swiss centres received either two s-r tablets of ibuprofen (daily dose 1600 mg; n = 30) or a single s-r diclofenac 100 mg tablet (n = 31) each evening for 21 days. Clinical assessments were performed prior to initiating therapy and after 7 and 21 days of treatment. Both treatments were efficacious, but statistically significant differences in favour of s-r ibuprofen were observed for the principal measure of efficacy, the investigator's assessment of the overall change in clinical condition; by Day 21, 37% of ibuprofen-treated patients vs 10% of diclofenac-treated patients were 'much improved' (p = 0.04). Patients' assessments of the efficacy of their treatment also favoured s-r ibuprofen at Day 7 for the relief of night pain (p = 0.048), at Day 21 for alleviation of day pain (p = 0.006) and for the ability to carry out normal activities (p = 0.01), and at both Days 7 and 21 for quality of sleep (p = 0.04 and 0.03, respectively). The patients' overall opinion of treatment was also significantly in favour of s-r ibuprofen, which was rated 'good or excellent' by 80% (24/30), compared with only 38% of patients (11/29) receiving s-r diclofenac sodium (p = 0.002). Two patients (6%) receiving s-r diclofenac sodium ceased treatment owing to dizziness and severe diarrhoea, respectively; there were no withdrawals in the ibuprofen-treated group. Ten (32%) patients in the s-r diclofenac group reported a total of 12 adverse events (mostly gastrointestinal in nature), compared with three (10%) patients in the s-r ibuprofen group who reported only three events (abdominal pain, insomnia and constipation). In conclusion, although both NSAID treatments improved the clinical condition of patients with painful osteoarthritis, statistically significant differences in favour of once-daily s-r ibuprofen (1600 mg) were demonstrated in terms of efficacy, indicating a potential therapeutic advantage for this formulation. Ibuprofen was also better tolerated than diclofenac sodium (100 mg/day), the latter being associated with gastrointestinal side effects in a significant proportion of patients. Sustained-release ibuprofen (Brufen Retard) thus represents an important addition to the available therapeutic armamentarium of once-daily NSAID formulations.

Activities of Daily Living↗
PubMed1995

Does the overexpression of pro-insulin-like growth factor-II in transfected human embryonic kidney fibroblasts increase the secretion of lysosomal enzymes?

Insulin-like growth factor-II (IGF-II) and lysosomal enzymes bearing the mannose 6-phosphate (Man6P) recognition marker, bind to two distinct binding sites of the IGF-II/M6P receptor. The two classes of ligands reciprocally modulate the binding of the other class of ligand to the receptor [Kiess, W., Thomas, C. L., Greenstein, L., Lee, L., Sklar, M. M., Rechler, M. M., Sahagian, G. G. & Nissley, S. P. (1989) J. Biol. Chem. 264, 4710-4714]. We asked whether or not overexpression of pro-IGF-II by cells in culture leads to missorting of lysosomal enzymes. Human embryonal kidney fibroblasts were transfected with the full-length human IGF-II cDNA or a control cDNA. Solution hybridization/RNase protection experiments using a human IGF-II riboprobe showed that two transfectants expressed large quantities of IGF-II mRNA, whereas the non-transfected cells did not. The analysis of conditioned media revealed that these cells secrete approximately 0.15 micrograms and 1.0 micrograms immunoreactive IGF-II/ml and 22 x 10(6) cells and 24 x 10(6) cells within 24 hours. Immunoreactive IGF-II was shown by Western blotting to represent 17-kDa pro-IGF-II. The amount of the lysosomal enzyme, beta-hexosaminidase, was approximately twofold increased in the conditioned media from pro-IGF-II overexpressing cells compared with control media, as shown by Western-blot analysis and immunoprecipitation of media extracts of metabolically labeled cells. The synthesis rate of beta-hexosaminidase was not affected by pro-IGF-II overexpression. In addition, the basal amount of another newly synthesized lysosomal enzyme, the cathepsin D precursor, was also twofold higher in pro-IGF-II overexpressing cells than in control cells. In contrast, the surface binding and cellular uptake rate of a Man6P-containing neoglycoprotein did not differ between the cell lines. The results indicate that the overexpression of pro-IGF-II doubles the secretion and/or reduces the re-uptake of beta-hexosaminidase and cathepsin D to approximately 20% of the total synthesized enzymes in human embryonal kidney fibroblasts compared to control cells. We hypothesize that, in cells synthesizing high amounts of pro-IGF-II, the growth factor may modulate the targeting of a portion of lysosomal enzymes, mainly by partially enhancing the secretion of newly synthesized enzymes and, in addition, possibly by affecting the re-uptake mechanism.

Cathepsin D↗
PubMed1994

The pathophysiology of the insulin-like growth factor axis in fetal growth failure: a basis for programming by undernutrition?

Recent evidence suggests that a number of adulthood conditions, including non-insulin dependent diabetes mellitus (NIDDM) and lipid and cardiovascular abnormalities are associated with intra-uterine growth retardation (IUGR). It is possible that this arises from programming of endocrine axes during development as a result of an adverse intra-uterine environment. Insulin-like growth factors (IGFs) are mitogenic polypeptides which stimulate cellular proliferation and differentiation and are important in human fetal development. The functions of IGFs are modulated by specific high affinity binding proteins (IGFBPs). IGFBP-1 is antagonistic to the insulin-like and growth promoting effects of IGF-I, and IGFBP-3 holds IGFs in the circulation by associating with IGFs and an acid labile subunit to form a ternary complex. Using specific radioimmunoassays and fetal serum obtained during diagnostic cordocentesis we have investigated the role of the IGF/IGFBP axis in human fetal development. In a study of 130 singleton pregnancies we have examined levels of immunoreactive IGFs and IGFBPs in normally grown fetuses (AGA), starved small fetuses affected by uteroplacental insufficiency (UPI), and non-starved small fetuses (SGA). IGF-I was significantly lower in the UPI group (n = 14, 7.8 +/- 0.6 micrograms l-1), than in either the SGA group (n = 22, 31.4 +/- 3.5 micrograms l-1, P = 0.0001) or the AGA group (n = 94, 36.3 +/- 1.9 micrograms l-1, P = 0.0001). IGFBP-3 showed similar changes (UPI: 682.6 +/- 50.0 micrograms l-1; SGA: 831.9 +/- 55.5 micrograms l-1; AGA: 847.7 +/- 19.8 micrograms l-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Carrier Proteins↗
PubMed1994

No evidence for reduced spontaneous or growth-hormone-stimulated serum levels of insulin-like growth factor (IGF)-I, IGF-II or IGF binding protein 3 in women with spinal osteoporosis.

To test the hypothesis that a dysfunctional growth hormone (GH)-insulin-like growth factor (IGF) axis may play a role in the pathogenesis of osteoporosis, we compared the levels of IGF-I, IGF-II and IGF binding protein 3 (IGFBP-3) in 15 women with spinal osteoporosis (i.e. at least one non-traumatic vertebral fracture) and 15 normal age-matched women. Furthermore, the response to 3 days' treatment with recombinant human GH (r-hGH) (0.2 IU kg-1.day-1) was determined. The basal levels of IGF-I, IGF-II and IGFBP-3 were similar in patients and controls (mean +/- SEM): IGF-I, 16.5 +/- 1.3 versus 16.0 +/- 1.3 nmol/l (NS); IGF-II, 79.9 +/- 3.6 versus 72.5 +/- 4.1 nmol/l (NS); and IGFBP-3, 125.7 +/- 6.5 versus 130.3 +/- 7.8 nmol/l (NS). Stimulation with r-hGH elicited increased levels of IGF-I, IGF-II and IGFBP-3 within both groups (p < 0.001). The maximal values expressed as a percentage of baseline were: IGF-I, 341 +/- 26% versus 369 +/- 22%, IGF-II, 125 +/- 4% versus 119 +/- 5%, IGFBP-3, 141 +/- 5% versus 147 +/- 7% in osteoporotic patients and controls, respectively. No significant differences were observed between patients and controls in either their maximal response or in the area under the response curves. Our results do not support the hypothesis of a dysfunctional GH-IGF axis in women with spinal osteoporosis.

Aged↗
PubMed1993

Human IM-9 lymphoblasts as a model of the growth hormone-insulin-like growth factor axis: gene expression, and interactions of ligands with receptors and binding proteins.

Human IM-9 lymphoblasts bind growth hormone (hGH) and insulin-like growth factors (IGFs). We have systematically examined the IM-9 cells as a valuable model of the interaction of hGH and the IGFs at the cellular level. Cells were cultured in medium with 10% serum and for a subset of experiments cultured in serum-free medium. Binding of [125I]hGH and [125I]IGF-I and -II to intact IM-9 cells was measured: unlabeled hGH inhibited binding of [125I]hGH (half max. 20 ng/ml). Binding of [125I]IGF-I was inhibited by IGF-I (half max. 7.5 ng/ml), IGF-II (half max. 60 ng/ml), and insulin and anti IGF-I receptor antibody (alpha IR3). [125I]IGF-II was inhibited by IGF-II (half max. 15 ng/ml), IGF-I (half max. 500 ng/ml), insulin (half max. 250 ng/ml) but not by alpha IR3. Crosslinking experiments with [125I]IGF-II and DSS as the crosslinking agent and analysis of radioligand-receptor complexes by SDS-PAGE under reducing conditions revealed that [125I]IGF-II bound to a 250 kDa and a 135 kDa receptor species. The latter possibly represents an insulin-type receptor whereas the 250 kDa species had the characteristics of the IGF-II/M6P receptor. When IM-9 cell conditioned medium was analyzed in ligand blotting experiments with either [125I]IGF-I or -II a 30 kDa IGFBP species was detected on the autoradiographs. Also, IGF-II immunoreactivity (approx. 1 ng/ml medium) was measured in the cell conditioned medium using an IGF-BP blocked RIA employing [125I]IGF-II. In a subset of experiments IM-9 cells were homogenized in 4 M guanidinium-thiocyanate and RNA extracted in 5.7 M CsCl. Denatured RNA was electrophoresed on 0.8% agarose gels and transferred to a nylon membrane, fixed and the blots hybridized with cDNA probes. Probes were labeled with [32P]dCTP using a random prime labeling procedure: a Pst I 700 bp fragment of the human IGF-I cDNA, a 554 bp Pst I-Sal I fragment of the IGF-II cDNA, a 614 bp Pst I fragment of the IGF-I receptor cDNA and a 663 bp Pst I fragment of the IGF-II/M6P receptor. Autoradiographs of Northern blots showed specific hybridization with the IGF-I probe at 3.7 kb and with the IGF-II probe at 5.3 kb. No signal was detected with the IGF-I receptor cDNA probe. Hybridization with the IGF-II/M6P receptor probe yielded a 9 kb RNA species.(ABSTRACT TRUNCATED AT 400 WORDS)

Binding, Competitive↗
PubMed1993

Growth hormone stimulates proliferation and differentiation of normal human osteoblast-like cells in vitro.

In this study we investigated the direct, short-term effects of human growth hormone (hGH) on the biology of normal adult human osteoblast-like (hOB) cells cultured from trabecular bone explants. In Subconfluent cultures, hGH stimulated hOB proliferation in a dose-dependent fashion (P < 0.001, n = 15) with half-maximal effects at a concentration of 10 ng/ml. These mitogenic effects were detectable within 24 hours as shown by bromodeoxyuridine labeling. In confluent cultures containing mainly quiescent cells, hGH increased levels of alkaline phosphatase (P < 0.05, n = 10) and to a lesser degree levels of procollagen type I carboxyterminal propeptide (PICP) (P = 0.07, n = 9). Effects on osteocalcin (bone GLa protein, BGP) levels were highly variable among different cell strains and only 7 of 10 cell strains showed a stimulatory response (P = 0.16). We also studied the effects of hGH on osteoblastic production of insulin-like growth factor I (IGF-I) and IGF-II as well as the production of GH-dependent, insulin-like growth factor binding protein 3 (IGFBP-3). Under basal conditions, human osteoblasts produced IGF-II and IGFBP-3 in the conditioned medium. When stimulated with hGH, minor insignificant increase in both IGF-II and IGFBP-3 (125% and 126% of control, respectively) were detectable. No IGF-I was detectable in the conditioned medium under basal conditions or after stimulation with hGH. In conclusion, the results obtained in this study suggest that GH exerts direct anabolic effects on human osteoblasts.

Alkaline Phosphatase↗
PubMed1993

Relationship between carbohydrate metabolism and serum insulin-like growth factor system in postmenopausal women: comparison of endometrial cancer patients with healthy controls.

Insulin is a major regulator of circulating insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1), suppressing the hepatic production of IGFBP-1. Postmenopausal age, obesity, hypertension, and impaired glucose tolerance, which are known risk factors for endometrial cancer, are all associated with hyperinsulinemia and insulin resistance. In this study, we investigated the relationship among serum insulin, glucose, insulin-like growth factors (IGF-I and IGF-II), and IGFBP-, -2, and -3 in 32 nondiabetic postmenopausal women with endometrial cancer and in 18 healthy controls. The mean fasting levels of glucose and insulin were higher, whereas the mean basal IGF-I, IGF-II, and IGFBP-3 levels were lower in the endometrial cancer patients than in the healthy control subjects. The mean fasting IGFBP-1 and IGFBP-2 levels did not differ between the groups, and no correlation was found between fasting insulin and IGFBP-1 concentrations or between insulin and IGFBP-2 concentrations in either of the study groups. During an oral glucose tolerance test, the mean glucose levels at 1 and 3 h as well as the mean insulin level at 3 h were significantly higher in the endometrial cancer patients than in the controls, and the area under the glucose curve was larger in the first group. An oral glucose load resulted in a similar fall in serum IGFBP-1 levels in endometrial cancer patients and controls (51% and 55% at 3 h). When the cancer patients were divided into two subgroups according to the body mass index (kilograms per m2), the obese group had higher glucose and insulin indices than the nonobese group. No difference was found by the same measures in healthy controls. The fasting serum IGFBP-1 levels tended to be lower in the obese than in the normal weight subjects, but the difference did not reach statistical significance. In summary, these results provide preliminary evidence that the inverse relation between fasting insulin and IGFBP-1, well established in children and young adults, disappears in elderly women, although short term suppression by insulin still occurs. Further, our data indicate that in addition to carbohydrate metabolism, postmenopausal women with endometrial cancer have alterations in their circulating IGF system compared to controls.

Aged↗
PubMed1993

Insulin-like growth factor (IGF) I and II and IGF binding protein (IGFBP) 1, 2 and 3 in serum from patients with Cushing's syndrome.

In the present study of twenty-two patients with Cushing's syndrome, serum insulin-like growth factor (IGF)-I concentrations were normal to high with an increased mean IGF-I concentration, 40% above that of healthy subjects of the same age (p < 0.001). Serum IGF-II concentrations were normal. The morning serum IGF binding protein (IGFBP)-1 concentrations were within the range of healthy controls. IGFBP-1 was inversely correlated to the IGF-I concentration (p < 0.001) and to the 24 h urinary cortisol excretion (p < 0.005) with a combined R squared value of 0.58. In contrast to IGFBP-1, serum IGFBP-2 and IGFBP-3 concentrations were elevated by 1.89 +/- 1.78 SD and 0.92 +/- 0.78 SD (mean +/- 2 SD), respectively. Although increased, the serum IGFBP-2 concentration was inversely correlated to the IGF-I concentration (r = -0.67, p < 0.001). Immunoreactive IGFBP-3 was increased in proportion to IGF-I and the molar ratio [IGFBP-3]:[IGF-I] + [IGF-II] was close to unity (1.04 +/- 0.14), as that of healthy subjects. In serum from patients with Cushing's syndrome, with increased immunoreactive IGFBP-3, there was a corresponding increase in intact glycosylated 40-43 kDa IGFBP-3 as determined by Western ligand blotting. Neutral size chromatography of serum from patients with Cushing's syndrome showed that IGF-I and IGFBP-3 immunoreactivity were predominantly found at the elution volume of the ternary 150 kDa IGF-I/IGFBP-3/acid labile subunit complex and a similar pattern was displayed by normal serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Increased insulin-like growth factor-II tissue concentrations during compensatory kidney growth in infantile rats.

Insulin-like growth factor (IGF)-I and IGF-II serum and kidney tissue concentrations were measured in compensatory kidney growth in infantile and adult rats. We hypothesized that the known switch from IGF-II in fetal life to IGF-I in adult life may be responsible for the different modes of compensatory kidney growth, which are mainly characterized by hyperplasia in infantile rats and hypertrophy in adult rats. While IGF-I serum concentrations increased with age in infantile rats, kidney tissue concentrations of IGF-I showed a similar increase in both age groups after uninephrectomy. In adult rats, serum and kidney tissue concentrations of IGF-II were unchanged by uninephrectomy. In infantile rats, however, a significant increase in both serum and kidney concentrations of IGF-II was observed with a maximum at day 5 after uninephrectomy. To investigate if compensatory kidney growth is dependent on hyperperfusion of the remnant kidney, the left renal artery was clipped in infantile rats. The clipped kidney showed growth retardation despite normal kidney tissue concentrations of IGF-I and IGF-II. The contralateral kidney was enlarged and IGF-II kidney concentrations were elevated. However, animals with one clipped kidney and nephrectomy of the contralateral kidney showed compensatory kidney growth of the clipped kidney combined with increased IGF-II kidney tissue concentrations. We conclude that IGF-II mainly promotes compensatory kidney growth in infantile rats by hyperplasia. Hyperperfusion of the remnant kidney seems to be unnecessary for initiation of compensatory kidney growth.

Aging↗
PubMed1992

Influence of antibodies against IGF-I, insulin or their receptors on proliferation of human acute lymphoblastic leukemia cell lines.

To evaluate the potential role of IGF-I and insulin as growth-promoting factors in malignant lymphocyte development, we examined established T-acute lymphoblastic leukemic (ALL) cell lines with increasing stage of differentiation, HSB2, HUT78, CEM, MOLT3, Jurkat, JM-P, JM-886, and four established preB- and B-ALL cell lines REH, SKW6 CESS, BJAB for production of IGF-I and growth in the presence of antibodies, directed against IGF-I or insulin or their receptors. Basal DNA synthesis of the early differentiated T-cell lines HSB2 and HUT78, as well as the B-cell line REH, could be inhibited in a dose-dependent manner by both monoclonal antibodies against IGF-I (ASC41) and antibodies against the IGF-I receptor (alpha-IR3), suggesting that IGF-I acts as an auto- or paracrine growth factor for these cells via the IGF-I receptor. From these cells HUT78 and REH secreted IGF-I into cell culture medium. DNA synthesis of the further differentiated T-cell lines CEM and MOLT3 was inhibited by alpha-IR3 and antibodies directed against the insulin receptor (RPN.538) and against insulin (RPN.1661). These results suggest that insulin via the IGF-I receptor or insulin receptor can function as an autocrine or paracrine growth factor in these T-ALLs. Proliferation of the most differentiated T-ALL Jurkat and JMP was inhibited only by alpha-IR3 and 2C2, an antibody directed against the IGF-II receptor, suggesting that IGF-I or IGF-II acting via the IGF-I receptor or IGF-II receptor may be involved in proliferation of these cell lines. Inhibition of the DNA synthesis by RPN.538 and RPN.1661 indicate a more important role for insulin in growth of leukemias of the B-ALL cell lines SKW6 and CESS.

Antibodies, Monoclonal↗
PubMed1992

Renal hemodynamics in recent-onset type II diabetes.

Glomerular hyperfiltration is thought to play an important role in the genesis of diabetic nephropathy. While hyperfiltration is well documented in early type I diabetes, the evidence for hyperfiltration in type II diabetes is conflicting. We investigated 16 nonproteinuric patients with recently diagnosed type II diabetes. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured as inulin clearance (CIN) and p-aminohippuric acid clearance (CPAH) using a constant infusion technique. Lean body mass was measured by densitometry (weighing under water). Renal hemodynamics were also measured in 31 healthy volunteers and six obese nondiabetic individuals. Median GFR in diabetics (133 mL/min/1.73 m2; range, 95 to 165) was significantly (P < 0.01) higher than in obese nondiabetic controls (median, 118; range, 95 to 139). Elevated GFR (ie, > 95th percentile of nonobese healthy controls) was found in 44% of patients. When GFR was factored for lean body mass, it was elevated in 50%. GFR did not correlate with fasting glucose, hemoglobin A1C (HbA1C), insulin-like growth factors, IGF-1 and IGF-2, or somatomedin-binding protein (SMBP). The findings document that hyperfiltration is common in recent-onset type II diabetics.

Adult↗
PubMed1992

Defective stimulation of proliferation and collagen biosynthesis of human bone cells by serum from diabetic patients.

We studied the influence of fasting serum from nine insulin-dependent diabetic children and adolescents under insufficient metabolic control on normal human bone cells in vitro compared with serum from eight sex- and age-matched controls. Cell number 24 h after plating was significantly less under diabetic serum, indicating impaired cell attachment, spreading and initiation of cell proliferation. Cell number after five days was reduced by 1% diabetic serum, while higher serum concentrations had diverging effects on osteoblast proliferation. Collagen synthesis of human osteoblasts was significantly reduced by 8% diabetic serum compared to 8% control serum, while synthesis of non-collagenous proteins was not affected. Duration of diabetes (several weeks up to 12 years) had no influence on these parameters. The serum from one patient, which was studied a second time under excellent metabolic control three months later, however, had lost its inhibitory influence on collagen synthesis of osteoblasts. The pattern of the interstitial collagen types I, III and V was not altered by diabetic serum. These results indicate that defective regulation of proliferation and collagen synthesis of osteoblasts by components present in human diabetic serum may be an important factor in the development of diabetic osteopenia. The negative influence might be explained in part by reduced levels of IGF-I and elevated levels of IGF binding protein-1 in the diabetic sera.

Adolescent↗