Growth hormone bioactivity evaluated by Nb-2 cell bioassay

Nb-2 cell bioassay is not specific for evaluating the biological activity of growth hormone (GH) since it relies on the ability of the hormone to Produce effects by cross-reacting with the lactogenic receptor of Nb-2 cells. We inhibited the mitogenic effect of the other lactogenic hormone that is human prolactin (hPRL), by adding a specific antibody against hPRL to each assay. The aim of the present work was to evaluate whether our modified Nb-2 bioassay was capable of assessing the biological activity alone of bGH We compared serum GH measurements using an immunofluorometric assay (IFMA) and the Nb-2 cell bioassay in serum samples collected from 11 idiopathic GH-deficient children, age range 1.2-14 years, before and, then, 6 and 24 hours following the 1st injection of r-bGH (0.1 IU/Kg sc). Serum GH values evaluated by both IFMA and Nb-2 bioassay significantly (p lt 0.0001) increased 6 hours after GH administration (from 1.36 +- 0.81 to 12.59 +- 1.77 ng/ml and from 0.55 +- 0.09 to 1.56 +- 0.24 U/ml, respectively), and decreased to reach basal levels after 24 hours. In conclusion, the Nb-2 cell bioassay with minor modifications seems to provide a specific and sensitive assessment of the biological activity of GH

Growth hormone bioactivity and levels of growth hormone, growth hormone-binding protein, insulinlike growth factor I, and insulinlike growth factor-binding proteins in premature and full-term newborns during the first month of life

Objective: To assess the pattern of growth hormone bioactivity (GH-BIO) and the levels of GH-binding protein (GH-BP), insulin-like growth factor I (IGF-I), and insulin-like growth factor-binding proteins (IGFBPs) in the first month of life in premature and full-term (FT) newborns. Patients and Methods: Serum samples were collected from 9 premature newborns who were small for gestational age, 18 premature newborns who were of appropriate size for gestational age, and 20 FT newborns on the 4th and 30th days of life to evaluate the GH-BIO using the Nb2 cell bioassay, the GH levels using a radioimmunoassay (GH-RIA), and the levels of GH-BP, IGF-I, and IGFBPs. Results: On day 4, the GH-RIA and GH-BIO values were increased in all newborns (P lt .05) compared with values in the prepubertal control subjects. The GH-BP levels were low in all newborns, with the lowest values (P lt .05) found in the premature newborns and positively correlated with gestation age (P lt .001). The IGF-I levels were also low, with lower values (than those found in the FT newborns) (P lt .005) found in the premature group and positively correlated with the GH-BP levels (P lt .001) and gestational age (P lt .001). The levels of IGFBP-1 and IGFBP-2 were high, with higher values found in the premature newborns than in the FT newborns (P lt .05) and negatively correlated with gestational age (P lt .005). The IGFBP-3 level was lower in the premature (P lt .05) than in the FT newborns and positively correlated with gestational age (P lt .005). During the first month of life, the GH-RIA and GH-BIO values were significantly decreased in all newborns (P lt .001), while the IGF-I level was increased in the premature newborns (P lt .005). The GH-BP levels were increased only in the FT newborns (P lt .001). Conclusions: The elevated bioactive GH level seen in the first few days of life seemed to be attributable to a low IGF-I level secondary to a decreased number and/or function of the GH receptors. The decrease in the serum GH level observed thereafter seemed to be secondary to an increase in the IGF-I level in the premature newborns; however, other factors may have been involved in the FT newborns in whom no increase in the IGF-I level was observed

Functional depletion of T cells by vincristine and methylprednisolone as an in vitro model for the prevention of graft versus host disease

The outcome of mismatched bone marrow transplantation is still severely hampered by graft versus host disease (GVHD) and graft rejection. Procedures for the recognition and selective elimination of T cells are still unsatisfactory due to the increased incidence of graft failure and late rejection. Lymphocyte proliferation and generation of cytotoxic T cells (CTL) in response to allogeneic cells are considered good in vitro correlates of GVHD and have been used in the present study to asses the capacity of two drugs (vincristine, VCR, and methylprednisolone, MP) to affect the T cells involved in these reactions. Treatment in vitro with VCR and MP has been shown to inhibit the functional capacity of peripheral blood lymphocytes to proliferate (mean reduction 95.8%) and to generate CTL in response to haploidentical stimulator cells. Responsiveness to antigens and mitogens was affected to a minor extent (mean reduction 40% and 65.5%, respectively), and the method allowed recovery of hemopoietic precursors. The results suggest that treatment of donor bone marrow with VCR and MP is worth studying as a new approach to the prevention of GVHD in haploidentical bone marrow transplantation

Implicazioni diagnostiche e prognostiche del gene NPM-ALK nel linfoma anaplastico a grandi cellule

Haematologic

Postnatal variations of growth hormone bioactivity and of growth hormone-dependent factors

Objective: To evaluate whether the low insulinlike growth factor I (IGF- I) levels that are observed in the neonate depend on the biological inactivity of the molecular forms of growth hormone (GH) or on the immaturity of the hepatic GH receptors during the early postnatal period. Materials and Methods: Serum samples were collected from 60 normal full-term neonates on day 5 and at 1 and 4 months of age to evaluate the GH concentrations by using both an immunofluorometric assay and Nb2 cell bioassay, as well as the GH- binding protein, IGF-1, and IGF-binding protein 3 values by radioimmunoassay. Results: Five-day-old neonates showed significantly higher (P<.001) mean±SEM GH levels that were measured by using the immunofluorometric assay (27.22±1.62 μg/L) and Nb2 cell bioassay (3.56±0.14 U/mL) compared with those levels in 11 prepubertal children who were studied as control subjects (1.26±0.28 μg/L and 0.74±0.08 U/mL, respectively). At 1 and 4 months of age, GH values that were measured by using both the immunofluorometric assay (9.15±089 and 2.58±0.32 μg/L, respectively) and Nb2 cell bioassay (2.52±0.11 and 1.71±0.15 U/mL, respectively) were decreased significantly (P<.001). In 5 day-old neonates, we observed significantly lower (P<.001) serum GH-binding protein (9.73%±0.42%), IGF-I (67.63±5.20 ng/mL), and IGF- binding protein 3 (1.46±0.17 mg/L) concentrations compared with those in the prepubertal children (30.74%±2.01%, 210±25 ng/mL, and 3.08±0.22 mg/L, respectively). At 1 month of age, serum GHbinding protein (16.00%±0.70%) and IGF-binding protein 3 (2.96±0.30 mg/L) values were increased significantly (P<.001), while IGF-I levels (72.55±7.6 ng/mL, P=.09) were not increased. Serum IGF-I values were increased significantly (P<.005) at 4 months of age (97.94±9.68 ng/mL). Conclusion: The interaction of bioactive molecular forms of GH with the increased hepatic GH receptors induces the rise in postnatal IGF-I levels in early infancy