Pharmacokinetics (PK) of S/D treated anti-D immunoglobulin after intramuscular injection in healthy volunteers: gender differences in PK.

The aim of this study was to investigate the pharmacokinetic profile of the new solvent/detergent (S/D) formulation of an anti-D IgG preparation, and to evaluate gender differences. RhD-negative subjects (m/f=10/8) received a single i.m. injection of 250 microg anti-D (Partobulin SDF). There was a rapid increase in median anti-D titers over the first 2 days, followed by a plateau from days 2-7. Interestingly, women had a higher maximum concentration (Cmax) of anti-D and a lower volume of distribution at steady state (Vss) than men. The half-life calculated in this study was 23 days. Thus, results are comparable to published data of the non-S/D treated predecessor product. Because of the observed gender differences in the pharmacokinetics we recommend to pursue the evaluation of sex differences in the pharmacokinetics of other antibodies during early phase drug development.     

Consideration of appropriate clinical applications for cardiac xenotransplantation

The field of cardiac xenotransplantation has entered an exciting era due to recent advances in the field. Although several hurdles remain, the use of rapidly evolving transgenic technology has the potential to address current allogeneic donor pool constraints and mechanical circulatory system device limitations. The success of xenotransplantation will undoubtedly be dependent on specific patient selection criteria. Defining these particular indications for xenotransplantation is important as we approach the possibility of clinical applications.     

Clinical benefit of prostaglandin E1-treatment of patients with ischemic heart disease: stimulation of therapeutic angiogenesis in vital and infarcted myocardium.

New evidence suggests that Prostaglandin E1 (PGE-1) stimulates myocardial angiogenesis in human chronic ischemic myocardium. We sought to investigate whether PGE-1 may participate in the process of neoangiogenesis within the myocardial infarct scar. Neovascularization was investigated in 14 explanted hearts from patients with ischemic cardiomyopathy, who had been bridged to heart transplantation (HTX) with PGE-1 and compared with 14 hearts from patients who did not receive PGE-1 prior to HTX. In transmural sections obtained from the left ventricular wall and containing myocardial scar tissue, CD34 and vascular endothelial growth factor (VEGF) were quantified immunohistochemically to estimate capillary density and amount of angiogenesis. Additionally, to assess the hypoxic state of myocardium of the infarct border zone, hypoxia inducible factor 1-alpha (HIF-1alpha) was determined by immunohistochemistry and quantified by means of planimetric analysis. PGE-1-treated patients had significantly more CD34-and VEGF-positive cells in infarct areas as compared to nonPGE-1 group, respectively (CD34: 116.7 +/- 5.9 vs. 45.1 +/- 5.2 capillary profiles/mm(2), P < 0.001, and VEGF: 48.3 +/- 4.9 vs. 22.9 +/- 4.7 capillary profiles/mm(2)). HIF-1alpha enrichment (in %) as well as staining intensity (in estimated units (eU)) was significantly decreased in PGE-1-treated as compared to non-treated controls (enrichment: 11.3 +/- 2.5% vs. 19.4 +/- 4.36%; staining intensity: 0.95 +/- 0.3 vs. 1.97 +/- 0.44 eU). Our data demonstrate that PGE-1 stimulates neoangiogenesis in infarct areas adjacent to viable myocardium, via upregulation of VEGF expression. The induction of therapeutic angiogenesis along with the improved hypoxic state of chronic ischemic myocardial tissue might explain the favorable clinical outcome in PGE-1 treated patients.     

Antagonist of growth hormone-releasing hormone induces apoptosis in LNCaP human prostate cancer cells through a Ca2+-dependent pathway

Antagonists of growth hormone-releasing hormone (GHRH) exert antiproliferative effects directly on cancer cells, which are mediated by the tumoral GHRH receptors. However, the signal transduction pathways involved in antiproliferative effect of GHRH antagonists have not yet been elucidated. We used flow cytometry to investigate whether GHRH antagonist JV-1-38 can induce changes in the cytosolic free Ca2+ concentration leading to apoptosis in LNCaP human prostate cancer cells. JV-1-38 evoked prompt Ca2+ signal in a dose-dependent way (1-10 microM) and induced early stage of apoptosis in LNCaP human prostate cancer cells at a concentration effective in suppression of cell proliferation (10 microM) peaking after 3 h. Unexpectedly, agonist GHRH(1-29)NH2, which elevates cytosolic free Ca2+ concentration in pituitary somatotrophs at nanomolar concentrations, failed to induce Ca2+ signal or apoptosis even at a 10-fold higher concentration (100 microM). However, agonist GHRH(1-29)NH2 inhibited JV-1-38-induced Ca2+ signals in a dose-dependent way without affecting the antagonist-induced apoptosis. Peptides unrelated to GHRH did not induce Ca2+ signals in LNCaP human prostate cancer cells. EDTA (10 mM) or nifedipine (10 microM) significantly reduced the Ca2+ signal and early stage of apoptosis induced by JV-1-38, supporting the view that the increase in intracellular Ca2+ in response to JV-1-38 occurs primarily through extracellular Ca2+ entry through voltage-operated Ca2+ channels. In conclusion, GHRH antagonists activate tumoral GHRH receptors and are able to induce apoptosis in LNCaP human prostate cancer cells through a Ca2+-dependent pathway. Treatment with GHRH antagonists may offer a new approach to the therapy of prostate and other hormone-sensitive cancers.     

Vasoactive intestinal peptide fibers innervate neuroendocrine dopaminergic neurons

Hypothalamic neuroendocrine dopaminergic neurons exhibit a diurnal rhythm. Higher level input to these neurons has not been described. In the present study, we identified fibers known to originate in the suprachiasmatic nucleus (SCN), which were associated with neuroendocrine dopaminergic neurons. Hypothalamic sections were obtained from either ovariectomized (OVX) female rats or OVX female rats implanted with estrogen and progesterone (E+P). Confocal microscopic images were acquired from the periventricular nucleus, as well as the rostral, dorsomedial, ventrolateral, and caudal regions of the arcuate nucleus. Using antibodies directed against vasoactive intestinal peptide (VIP) and tyrosine hydroxylase (TH) the rate-limiting enzyme in dopamine synthesis, fine VIP fibers in close apposition to TH-immunoreactive (IR) soma and proximal dendrites were revealed. Of the antibodies for the two VIP receptor subtypes (VIP1R and VIP2R), only VIP2R was found on TH-IR neurons. E+P significantly increased the incidence and density of neuroendocrine dopaminergic neurons expressing VIP2R, when compared to OVX animals. E+P did not affect the percent of neuroendocrine dopaminergic neurons associated with VIP fibers. No VIP fibers or VIP2R were found on dopaminergic neurons in the zona incerta. Brain sections triple labeled for Synapsin (a protein localized in synaptic vesicles) VIP, and TH demonstrated that Synapsin was colocalized with VIP fibers that were associated with TH-IR neurons in the arcuate nucleus. Double-label immuno-electron microscopy of hypothalamic sections labeled with antibodies for VIP and TH revealed VIP boutons associated with TH-IR soma and proximal dendrites. These results suggest VIPergic neurons may directly regulate neuroendocrine dopaminergic neuron activity, and ovarian steroids may play a modulatory role.