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Biomedical subjects

P Del Monte

Publications and source records attributed to P Del Monte.

At least 37 records · Page 2Linked to original sources
PubMed1992

In vitro paracrine regulation of human keratinocyte growth by fibroblast-derived insulin-like growth factors.

Human keratinocytes isolated from a skin biopsy and cultured in vitro on a feeder-layer of irradiated fibroblasts reconstitute a stratified squamous epithelium suitable for grafting onto patients suffering from large burn wounds. Since conditioned medium from 3T3-J2 cells can partially substitute for the intact feeder-layer, we studied the possible involvement of insulin-like growth factors acting in a paracrine fashion. IGFs were measured (after Sephadex G-50 gel-chromatography in acid conditions) in media conditioned by a feeder-layer of lethally irradiated 3T3-J2 fibroblasts on which keratinocytes were grown. Immunoreactive (IR) IGF-I, IGF-II, and IGF binding activity were present in the medium conditioned by the feeder-layer. The medium conditioned by keratinocytes showed nearly undetectable amounts of IR IGF-I and IGF-II, suggesting that keratinocytes are unable to synthesize IGFs peptides. Recombinant IGF-I and IGF-II, and conditioned medium from 3T3-J2 cells, caused a dose-dependent increase of 3H-thymydine incorporation in cultured keratinocytes. The stimulatory effect of IGF and of 3T3-J2 conditioned medium was inhibited by the MoAb Sm 1.2, which recognizes both IGF-I and IGF-II but not insulin, and by the MoAb alpha IR-3, which is a specific antagonist of type-I IGF receptor. Fetal mouse-derived 3T3-J2 cells and adult human skin fibroblasts were equally able to sustain keratinocyte growth and in both cases addition of Sm 1.2 MoAb causes a 50% decrease in the keratinocyte number. When the non-IGF-producing BALB/c 3T3 cells were used as a feeder-layer, the keratinocytes number was similar to that observed with 3T3-J2 and with human fibroblasts plus the Sm 1.2 MoAb. IGF-I and IGF-II restored the BALB/c 3T3 growth promoting activity to the level of 3T3-J2 and of normal human fibroblasts. Our results suggest that fetal mouse 3T3-J2 and human fibroblasts synthesize IGF peptides, while keratinocytes do not. Fibroblast-derived IGFs stimulate keratinocyte growth in a paracrine fashion, suggesting their role in the regulation of keratinocyte proliferation in skin growth and in wound healing.

Animals↗
PubMed1991

Paracrine actions of IGF binding proteins.

The paracrine mode of action for IGFs has been hypothesized on the basis of the finding that these peptides are synthesized ubiquitously. As IGFs circulate in very high concentrations (nearly 1 mg/l) they should have an endocrine function; moreover since the liver seems to be responsible for most of the circulating IGF-I it should be recognized that the basis of the "hormonal" IGF-I residues in the liver, whereas the extrahepatic synthesis provides support for local paracrine or autocrine actions. According to the endocrine hypothesis, the liver, which lacks IGF-I receptors, produces both IGF-I and IGF binding protein (IGFBP) and, possibly, the acid-labile subunit. All these components combine in the circulation, and only free IGF-I or small molecular weight complexes cross the capillary wall and reach the target cells. The paracrine hypothesis is based on the fact that fibroblasts are able to synthesize both IGF peptides and IGFBP, whereas keratinocytes are not, although they possess IGF receptors and are sensitive to IGF action. Since affinity of BP3 (which seems to be produced by peripheral fibroblasts) for IGF-I is higher than that of fibroblasts and, to a lesser degree, of keratinocytes, it is likely that IGF-I released from fibroblasts preferentially binds to BP3; the BP3-IGF-I complex reduces the autocrine effects on fibroblasts and preferentially directs the peptide binding to keratinocytes. The secretion of both IGFs and of IGF carrier proteins has been reported in several neoplastic epithelial cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Insulin-like growth factor-I (IGF-I) and IGF-I binding protein in the follicular fluids of growth hormone treated patients.

The presence of GH, insulin-like growth factor-I (IGF-I), epidermal growth factor (EGF), oestradiol (E2) and progesterone (PG) were investigated in the fluids obtained from various ovarian follicles of seven patients in whom the induction of super-ovulation was achieved only after GH (0.1 U/kg BW/day) was added to the gonadotrophin therapy. The follicular fluids of six patients responsive to treatment with gonadotrophin alone served as a control. In patients treated with combined therapy, the results demonstrated the presence in the follicular fluids of GH (M +/- SEM: 8.5 +/- 0.6 mU/l), E2 (771 +/- 38 nmol/l), and PG (16.4 +/- 0.7 pmol/l) in significantly higher concentrations compared to that in control follicles (6.2 +/- 0.8 mU/l, 681 +/- 30 nmol/l, and 14.4 +/- 0.6 pmol/l; P = 0.002, 0.012, 0.0001 respectively). Acid-extractable IGF-I (143 +/- 9 ng/ml) and EGF (3.9 +/- 0.3 ng/ml) concentrations were similar to those of control fluids (124 +/- 10 ng/ml and 2.9 +/- 0.7 ng/ml respectively) and were highly correlated with each other (P less than 0.001), suggesting a stimulatory effect of EGF on the local IGF-I production. A correlation between GH and IGF-I (n = 51, r = 0.36), as well as between IGF-I and PG (n = 48, r = 0.77) and E2 (n = 48, r = 0.55) was evident only in the follicular fluid of GH-treated subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Immunoreactive insulin-like growth factor I (IGF-I) and IGF-I-binding protein content in human thyroid tissue.

We measured immunoreactive insulin-like growth factor I (IGF-I) in extracts of normal and nodular thyroid tissue obtained at surgery from patients with nontoxic goiter. The nodular tissues contained a higher concentration [mean, 279.0 +/- 69.7 (+/- SE) mU/g] than paired normal tissues (115.5 +/- 17.9 mU/g; P = 0.024; n = 12); a difference was evident in all but one patient. Sephadex G-50 gel filtration of tissue extracts revealed two immunoreactive peaks, the first in the void volume of the column, and the second in the elution volume of authentic IGF-I. The first peak was identified as IGF-I-binding protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after cross-linking with iodinated IGF-I. Isolated thyroid cell membranes contained high affinity IGF-I-binding sites of similar affinity and numbers in both normal and nodular thyroid tissue. The IGF-I content of six thyroid cancer extracts was higher than that of normal thyroid tissue, but the IGF-I content of thyroid tissue from six patients with Graves' disease and five patients with Hashimoto's thyroiditis was similar to that in normal thyroid tissue. These data suggest that the stimulatory effect of TSH on thyroid cell proliferation could be mediated through IGF-I action and suggest that an increase in IGF-I production could sustain the goitrogenic process.

Adult↗
PubMed1988

Epidermal growth factor in breast cyst fluid: relationship with intracystic cation and androgen conjugate content.

In recent years, several studies focused on the biochemical analysis of breast cyst fluid composition. It has been shown that breast cysts lined by apocrine epithelium contain higher levels of potassium and dehydroepiandrosterone-sulphate as compared to cysts lined by flattened cells, and that women with apocrine cysts are more likely to develop breast cancer. In the present study, we measured the intracystic levels of sodium (Na+), potassium (K+), dehydroepiandrosterone-sulphate (DHEA-S), and epidermal growth factor (EGF), a factor which could play a role in the autocrine or paracrine control of breast cancer cell growth as recently proposed by some investigators. Breast cyst fluids obtained by fine-needle aspiration from 86 women with gross cystic breast disease were assayed. On the basis of the relative intracystic concentrations of Na+ and K+ two main classes of cysts were defined. An arbitrary cut-off value of 3 for the Na+/K+ ratio seemed adequate to separate these two types of cysts. An inverse relationship was found between the Na+/K+ ratio and DHEA-S concentration, median levels of the androgen conjugate being 3615 micrograms/dl in Na+/K+ less than 3 cysts and 480 micrograms/dl in Na+/K+ greater than 3 cysts (P less than 0.001). EGF levels were found to be significantly higher in Na+/K+ less than 3 cysts as compared to Na+/K+ greater than 3 cysts: 103.26 ng/ml versus 57.22 ng/ml, respectively (P less than 0.001). EGF appeared inversely correlated with total protein concentration in the Na+/K+ greater than 3 cysts, while in the Na+/K+ less than 3 cysts high EGF levels were observed independently of total protein content. In addition, a direct correlation was found between EGF and DHEA-S concentrations. On the basis of these results, the hypothesis can be made that EGF, which is measurable in all breast fluids tested and is nearly undetectable in plasma, is actually produced by the epithelium lining the cyst wall, particularly as far as the Na+/K+ less than 3 cysts are concerned. In view of our results this type of cyst, which has been shown to be lined by apocrine epithelium, appears to be characterized by high DHEA-S and EGF levels. It is suggested that the latter finding could provide a clue for understanding the increased risk of subsequent breast cancer in women bearing apocrine cysts.

Adult↗
PubMed1988

Evidence for autocrine mitogenic stimulation by somatomedin-C/insulin-like growth factor I on an established human lung cancer cell line.

The production of immunoreactive somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) by the established cell line derived from a human lung carcinoma CALU-6 has been evidenced in the serum-free medium in increasing concentrations as a function of the incubation time. Gel filtration in acid conditions of cell-conditioned medium collected after 72 h showed peaks of immunoreactive Sm-C/IGF-I in the elution volume corresponding to the molecular weight of the synthetic Sm-C/IGF-I, and in the high molecular weight region, where specific binding sites for Sm-C/IGF-I could be also demonstrated. These results indicate that this established cell line produces high amounts of immunoreactive Sm-C/IGF-I and of Sm-C/IGF-I carrier protein. The pooled fractions corresponding to the molecular weight of synthetic Sm-C/IGF-I showed a competitive binding curve parallel to the standard in the Sm-C/IGF-I RIA system, and a mitogenic activity on cells from the same line similar to the one observed using two different pure Sm-C/IGF-I preparations, obtained by chemical synthesis or by DNA recombinant technology. When a monoclonal antibody (sm-1.2) raised against Sm-C/IGF-I was added into the medium, the mitogenic effect observed by both synthetic and cell-derived Sm-C/IGF-I peptide was completely abolished; the monoclonal antibody also partially inhibited the effect of 10% fetal calf serum and the thymidine incorporation observed in serum-free medium without growth factors. In serum-free medium the monoclonal antibody produced a 45% reduction of cells in S phase by thymidine labeling index without modification of the growth fraction as determined by primer-dependent alpha-DNA polymerase labeling index. In conclusion it seems that Sm-C/IGF-I has a critical role in the autocrine stimulation of the replication of this cell line.

Antibodies, Monoclonal↗
PubMed1987

The GH-releasing hormone (GHRH) test in acromegaly before and after adenomectomy.

The GHRH test may represent a new tool in the study of GH dynamics in acromegaly. GH responsiveness to GHRH 1-40 (50 micrograms iv) has been studied in 21 acromegalic patients. Nineteen out of 21 had active disease. Five patients were also studied 1-12 months after neurosurgery. Two apparently cured acromegalics were studied 1-2 yr after surgery. GH secretion has been evaluated in all patients by means of TRH, bromocriptine and insulin hypoglycemia tests, too. GH response to GHRH has also been performed in 14 normal subjects. In acromegaly, GH responses after GHRH (p less than 0.01 vs placebo) were variable. The GH peak ranged from 8 to 445 ng/ml in patients with active disease. Maximum GH increase after GHRH (calculated as peak/basal value ratio) was significantly reduced in acromegaly (2.9 +/- 0.5 ng/ml; mean +/- SE) in comparison to controls (34.1 +/- 10.9 ng/ml; p less than 0.01). No significant differences in GH pattern after GHRH were found between untreated and previously treated patients with active disease. A significant correlation was found between GH basal levels and GH incremental area (p less than 0.05) and between GH basal and peak levels (p less than 0.01) after GHRH. A significant increase in PRL secretion was observed in acromegalic patients after GHRH (p less than 0.01 vs placebo). No discernable variation was found in the other pituitary hormones pattern after the peptide administration. A positive correlation was observed between GH increase after GHRH and insulin hypoglycemia (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1987

Partial characterization of somatomedin C-like immunoreactivity secreted by breast cancer cells in vitro.

The in vitro secretion of immunoreactive somatomedin C/insulin-like growth factor I (IR Sm-C/IGF-I) by two human breast cancer cell lines, MCF-7 and EVSA-T has been studied. IR Sm-C/IGF-I concentration showed a linear increase in serum-free culture media over 72 h of incubation for both cell lines, and a close correlation with cell number (P less than 0.001). To characterize this immunoreactivity, a pool of conditioned media collected after 72 h of incubation was dialyzed overnight against 1 M acetic acid, lyophilized, and gel filtered on a Sephadex G-50 column. Fractions were determined for Sm-C/IGF-I content and for the presence of a specific carrier for Sm-C/IGF-I. Two peaks of Sm-C/IGF-I-like immunoreactivity were evidenced, the first in the high molecular weight region and the second corresponding to the molecular weight of the free peptide. The first peak evidenced also a specific binding ability for radioiodinated Sm-C/IGF-I, suggesting that the activity found in this region could be interpreted as interference of the specific free binding sites in the immunoassay. Analysis of this peak by polyacrylamide gel electrophoresis demonstrated the presence of a specific binding for Sm-C/IGF-I in a molecular weight range between 35,000 and 45,000 Da, which was not modified in reducing conditions. The binding activity was competitively inhibited by addition of cold Sm-C/IGF-I but not by insulin excess.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗
PubMed1986

Growth hormone and somatomedin-C response to synthetic human pancreatic tumor GH-releasing factor in hypopituitary and constitutionally short children.

GH and somatomedin-C response to acute hpGRF-44 iv administration (1 microgram/Kg bw) was studied in 16 patients with hypopituitarism (GHD) and in 7 constitutionally short subjects. GH-deficient patients evidenced a significant GH increase peaking between 15 and 60 min. (4.95 +/- 0.88 ng/ml, mean +/- SE) (p less than 0.01 vs placebo). In non GH-deficient subjects GH increase was more pronounced (peak 18.00 +/- 3.01 ng/ml; p less than 0.01 vs both placebo and GHD group). Acid-extractable somatomedin-C was slightly, but significantly higher than baseline at 12th h (p less than 0.01) in both patients with hypopituitarism (basal value: 0.067 +/- 0.021 U/ml; 12 h: 0.096 +/- 0.024 U/ml) and constitutionally short subjects (basal value 0.62 +/- 0.13; 12h 0.72 +/- 0.16 U/ml). In 3 subjects with hypopituitarism multiple iv administrations (1 microgram/kg bw at 09:30 and 21:30 h for 4 days) produced on the average a modest increase of the GH responsiveness, were more effective to enhance somatomedin-C concentration, but not sufficient to reach normal levels. Sc administration of the same dose at 4-h intervals by a programmable portable pump - performed on 6 GHD subjects - produced an increase of GH peak response on the 4th day of treatment (1.38 +/- 0.31 ng/ml) with respect to the one observed on the first day (0.42 +/- 0.09 ng/ml). Somatomedin-C increase was low and inconstant. These data support the use of a 4-5-day pulsatile treatment in the differentiation between hypothalamic and pituitary deficiency, and the possibility of therapeutical use of GRF with the same protocol when a response is evidenced.

Adolescent↗
PubMed1986

Partial purification and characterization of a neutral insulin-like growth factor. Biochemical and biological properties.

A peptide with an isoelectric point of 6.5-7.0 was purified from Cohn fraction IV on the basis of its capacity to cross react with labelled insulin to human placental cell membrane receptors. It possesses insulin-like activity in the adipocyte bioassay (30 mU insulin equivalent/mg of protein) which is in the same order as its activity in the insulin radioreceptorassay (25.5 mU/mg). Somatomedin bioactivity is 40 U/mg in the porcine cartilage assay. In contrast, although in quiescent human fibroblast this peptide preparation has 6% of the mitogenic potency of somatomedin-C/insulin-like growth factor I on a weight basis, cross-reactivity in radioimmunoassay for somatomedin-C/insulin-like growth factor I, insulin-like growth factor II and insulin are very low. It is concluded that this peptide, although exhibiting the major biological characteristics of an insulin-like growth factor is different from the hitherto described somatomedins.

Adipose Tissue↗
PubMed1986

Evidence for an increased somatomedin-C/insulin-like growth factor I content in primary human lung tumors.

Immunoreactive somatomedin-C/insulin-like growth factor I (SM-C/IGF I) content was measured in human neoplastic lung tissue obtained from surgery on 10 patients (seven epidermoid carcinoma, three adenocarcinoma), and in normal lung tissue obtained from the same excised portion. SM-C/IGF I content in lung tumors was 615 +/- 123 (SE) milliunits/g of tissue (range, 214-1531), significantly higher (P less than 0.01) than normal tissue (234 +/- 51 milliunits/g of tissue; range, 37-537); in particular, every subject showed a clear-cut difference of SM-C/IGF I content between neoplastic and normal tissue (ratio, 3.41 +/- 0.69; range, 1.4-7.2). The results were essentially unchanged when data were expressed relative to hemoglobin or DNA tissue content. By contrast, in peripheral plasma SM-C/IGF I concentration was 0.51 +/- 0.17 units/ml, significantly lower (P less than 0.01) than in 59- to 70-yr-old control subjects (1.10 +/- 0.13 units/ml). In conclusion, the lung tumors studied, irrespective of their histological structure, contain more SM-C/IGF I than does normal tissue. Whether this is due to a primary in situ production of SM-C/IGF I or is secondary to overproduction of other inducers such as platelet derived growth factor-like peptides is yet to be clarified. The reduced circulating SM-C/IGF I concentration seems to be related more to the nutritional status of the patients.

Aged↗
PubMed1984

Prolactin secretion in pubertal and adult male subjects.

Prolactin, LH and FSH circadian secretion were studied in a group of 20 boys in various pubertal stages and in 13 normal male adults. Prolactin 24-hour integrated concentration was similar in all groups except in stage 2 boys, in which it was significantly higher with respect to stage 3-4 boys. This pattern was observed also for nocturnal, but not for diurnal concentration. As already described by other authors, LH showed and amplified circadian secretion in stage 2 and 3-4 boys, particularly during night time. FSH increase was less evident, and reached the peak 24-hour mean concentration in stage 2 subjects. Our results suggest that during puberty the hypothalamic pituitary system increases its activity not only with regard to gonadotropins but also to prolactin secretion.

Adolescent↗
PubMed1984

In vivo and in vitro effect of liver on somatomedin generation.

The serum concentration of circulating somatomedins was measured in the blood of healthy donors and subjects with hepatic cirrhosis, and in culture media from in vitro explants of healthy and cirrhotic human liver. Serum levels of somatomedin bioactivity were significantly lower in cirrhotic subjects (0.42 +/- 0.03 U/ml; M +/- SEM) compared with age matched controls (0.99 +/- 0.03 U/ml). Radioreceptor assay of somatomedin concentrations confirmed this reduction in cirrhotic patients (0.89 +/- 0.06 U/ml) compared with controls (1.32 +/- 0.05 U/ml). A parallel reduction in somatomedin circulating binding ability was also observed (99.43 +/- 7.28% in cirrhotic and 123.5% +/- 10.8% in normal subjects). In vitro explants from normal human liver tissue produced a significant increase (0.57 +/- 0.09 U/ml) in somatomedin bioactivity contained in the medium (0.29 +/- 0.06 U/ml), while a decreased bioactivity (0.12 +/- 0.06 U/ml) was observed with explants of cirrhotic livers. These results support a role of liver in the biosynthesis of both somatomedin and somatomedin binding protein.

Adult↗
PubMed1982

Growth hormone secretion in pubertal and adult subjects.

GH responsiveness to insulin-induced hypoglycaemia and its circadian secretion were studied in a group of subjects in different pubertal stages. The GH peak after insulin was minimal in stage 1 boys (7.6 +/- 1.3 (SEM) ng/ml) and increased progressively, in parallel with pubertal maturation, reaching a maximum in the adult state (20 +/- 4.0 ng/ml); the basal value was superimposable in all groups studied. The circadian secretion showed a sleep-related surge which was almost identical in the different stages; however in pubertal stage 1 boys multiple secretory peaks were observed, mainly during waking hours. A statistically significant difference (P less than 0.05) was observed in the mean concentration recorded during the day with a maximum in stage 1 boys (2.7 +/- 0.2 ng/ml) and a gradual decrease to a minimum in adults (1.2 +/- 0.3 ng/ml). This pattern seems to suggest that pulsatile rhythm is present in boys, similar to that observed for gonadotrophins.

Adolescent↗
PubMedDate not supplied

Spontaneous growth hormone and somatomedin-C/insulin-like growth factor-I secretion in obese subjects during puberty.

It has been reported that adult obese subjects present a reduced growth hormone secretion. As no data are available in the pubertal period, which is characterized in lean subjects by an increased spontaneous growth hormone secretion, the growth hormone circadian concentration was studied in a group of 18 obese male subjects in different pubertal stages, and compared to 26 age-matched control subjects. The data observed evidenced no statistically relevant differences regarding LH and FSH circadian secretion and morning testosterone concentration. On the contrary a statistically significant (p less than 0.02) difference in growth hormone 24 h integrated concentration was evident, particularly in prepubertal subjects; the sleep-related peak was evident in 28% of obese subjects and in 85% of controls. Sm-C/IGF-I concentration was similar to the concentration observed in controls in the prepubertal stage, but did not show the expected increase in the late puberty. Auxological data, performed on a sample of 80 subjects, showed both advanced height and bone age at beginning of puberty, and a trend toward a reduction of percentile for height in parallel with the pubertal maturation, suggesting that pubertal growth spurt in obese subjects is at least less pronounced than in lean subjects. It is concluded that GH and Sm-C/IGF-I secretion is impaired during puberty in obese subjects, leading to a reduced growth rate, while in the prepubertal period factors other than GH may replace or even potentiate its action.

Adolescent↗