Noninvasive Assessment of Tumor VEGF Receptors in Response to Treatment with Pazopanib: A Molecular Imaging Study

Vascular endothelial growth factor (VEGF) and its receptors (VEGFRs) drive angiogenesis, and several VEGFR inhibitors are already approved for use as single agents or in combination with chemotherapy. Although there is a clear benefit with these drugs in a variety of tumors, the clinical response varies markedly among individuals. Therefore, there is a need for an efficient method to identify patients who are likely to respond to antiangiogenic therapy and to monitor its effects over time. We have recently developed a molecular imaging tracer for imaging VEGFRs known as scVEGF/^99mTc; an engineered single-chain (sc) form of VEGF radiolabeled with technetium Tc 99m (^99mTc). After intravenous injection, scVEGF/^99mTc preferentially binds to and is internalized by VEGFRs expressed within tumor vasculature, providing information on prevalence of functionally active receptors. We now report that VEGFR imaging readily detects the effects of pazopanib, a small-molecule tyrosine kinase inhibitor under clinical development, which selectively targets VEGFR, PDGFR, and c-Kit in mice with HT29 tumor xenografts. Immunohistochemical analysis confirmed that the changes in VEGFR imaging reflect a dramatic pazopanib-induced decrease in the number of VEGFR-2⁺/CD31⁺ endothelial cells (ECs) within the tumor vasculature followed by a relative increase in the number of ECs at the tumor edges. We suggest that VEGFR imaging can be used for the identification of patients that are responding to VEGFR-targeted therapies and for guidance in rational design, dosing, and schedules for combination regimens of antiangiogenic treatment.     

Restoration of morphological and functional integrity in the regenerating eye of the giant African land snail Achatina fulica

To determine whether vision returns to its original state following eye removal in Achatina fulica, light and electron microscope examinations, electrophysiological recordings and behavioural tests were carried out on the regenerating snails. Reparative morphogenesis can result in the restoration of the peripheral sense organ even in the absence of complete regrowth of the tentacle, but it can also lead to the formation of aberrant regenerates. We found that anatomically and ultrastructurally the eyes of the ‘most normal’ regenerates were basically the same as the original eyes. Under normal conditions each eye is composed of a principal and an accessory eye, both sharing a common cornea. The only difference between regenerated and native eyes is the smaller size of the former, as a result of a reduced number of retinal cells. Electroretinographic responses revealed that the molecular mechanism of phototransduction is restored, in principle, but that flicker fusion frequency in the regenerated eye is significantly lower than in the normal eye. The directional movement to a visual stimulus (a black stripe of 45° width) had not completely recovered even 6 months after amputation. This suggests that the central projections of the optic nerve had not become fully re‐established at the time of testing.     

External factors involved in the regulation of an extracellular proteinase synthesis in Bacillus megaterium

Summary A mathematical model was formulated to describe the kinetics and stoichiometry of growth and proteinase production in Bacillus megaterium. Synthesis of the extracellular proteinase in a batch culture is repressed by amino acids. The specific rate of formation of the enzyme (r _E) can be described by the formula {ie373-1}, where k ₂ and k ₃ stand for the non-repressible and repressible part of enzyme synthesis respectively, k _{S 2} is a repression coefficient and S ₂ indicates the concentration of amono acids; the values of k ₂ and k _{S 2} depend on the composition of the mixture of amino acids. Even in a high concentration, a single amino acid is less effective than a mixture of amino acids. The dependence of the proteinase repression on the concentration of an external amino acid (leucine) follows the same course as its rate of incorporation into proteins, approaching saturation at concentrations higher than 50 M (half saturation approximately 10 M). However, the total uptake of leucine did not exhibit any saturation even at 500 M external concentration.Symbols X biomass concentration, g/l - E proteinase concentration, unit/l - t time, h - S ₁ concentration of glucose, g/l - S ₂ concentration of amino acids, g/l - specific growth rate, l/h - rE specific rate of enzyme production, unit/g/h - k ₁ growth kinetic constant, l/h - k ₂ product formation kinetic constant (for non-repressible part of enzyme synthesis), unit/g - k ₃ product formation kinetic constant (for repressible portion of enzyme synthesis), unit/g - k _{S 1} saturation constant, g/l - k _{S 2} repression coefficient for a certain amino acid or amino acids mixture, g/l     

Physiological activity of immobilized cells of Claviceps fusiformis during long-term semicontinuous cultivation

Summary The 550-day semicontinuous cultivation of Claviceps fusiformis immobilized in calcium alginate is documented. The vegetative mycelium from seed or from early-production submerged culture is the best choice for immobilization. No extracellular glucans are produced by immobilized cells. Immobilized spores give low yields of clavine alkaloids. Alginate concentrations in a range of 2%–4% do not influence yield and spectrum of alkaloids. The cytoplasm of the immobilized cells becomes condensed (after 3 days), polysaccharides disappear, and centres of lipid synthesis are formed in the cytoplasm. After 60 days the cells harbour a great number of lipid particles, mitochondria are diminishing and their cristae partly disappear, indicating a decreased respiration capacity. After 350–500 days the volume of most cells is increased many times and the cells are filled with large oval bodies of electrondense material. Chloramphenicol protects immobilized cultures against bacterial contamination.     

Xfin: an embryonic gene encoding a multifingered protein in Xenopus.

The Xenopus laevis genome was screened for putative DNA-binding gene products by using the 'finger' region of the Drosophila gene Krüppel as a probe. The one gene detected, named Xfin, codes for a protein with 37 finger domains that comprise nearly 90% of the protein. In the light of studies by Rhodes and Klug (Cell, 46, 123-132, 1986), these data suggest that the Xfin protein has the capacity to bind an unusually large stretch (185 bases) of DNA. The Xfin gene is expressed as a maternal and zygotic mRNA that undergoes extensive polyadenylation changes during early development. The Xfin mRNA expression pattern and the potential DNA binding activity of the protein point to the possibility that the Xfin gene may have a role in controlling gene activity during early embryonic development.     

Antimicrobial effects of some mono- and bishydrazones

Antibacterial, antifungal and antiprotozoal effects of nine mono- and bishydrazones of glycolaldehyde, glyoxal, methoxyacetaldehyde and glutaraldehyde were studied using eight model organisms. It was found that bishydrazones are much more efficient antimicrobial agents than monohydrazones in the case of all model microorganisms.     

Mapping of the gene for anti-müllerian hormone to the short arm of human chromosome 19

The gene coding for human anti-Müllerian hormone (AMH) was localized to subbands p13.2----p13.3 on chromosome 19, using in situ hybridization and Southern blot analysis of a panel of man-mouse and man-hamster somatic cell hybrids.     

Human carcinoma cell lines xenografted in athymic mice: biological and antigenic characteristics of an intraabdominal model

Summary In order to investigate in vivo clinical applications of murine monoclonal antibodies directed against human ovarian carcinoma a preclinical in vivo model was developed using BALB/c athymic mice. Three human carcinoma cell lines (MCF7, HT29, and SW626) were injected into the peritoneal cavity of pristane-primed animals and the biological and antigenic characteristics of the i.p. grown tumors were studied. The animals were killed when moribund or 6–8 weeks after tumor injection. At autopsy tumor take was observed in 85% of the injected animals, whereas palpable nodules were evident in only 83%. Examination of the peritoneal cavity revealed intraabdominal carcinomatosis with tumor masses varying in size between 0.2 and 0.5 cm in diameter and tumor sheets. The most frequently affected organs were the diaphragm, the liver, and the reproductive system. Ascitic fluid formation was rare and no animal developed tumors outside the peritoneal cavity. To determine whether the in vivo tumors retained the same antigenic characteristics as the in vitro cell lines, four monoclonal antibodies (MBrl, MOv2, MOv8, and MOv15) directed against ovarian carcinoma-associated antigens and two different experimental approaches (immunofluorescence and immunoblotting) were used. Variations at either a quantitative or a qualitative level were observed for some antigens, whereas no evident changes were apparent for others. In particular, the antigens detected by MBr1 and MOv15 on the MCF7 line both maintained high levels of expression and immunoblotting staining pattern, whereas the antigens detected by MOv2 on the HT29 and SW626 lines, although present at a high level, clearly changed their staining pattern. As regards the antigens recognized by MOv8 and MOv15 on the HT29 and SW626 lines, we observed a drastic decrease in the level of their expression and in many cases a drop below the threshold of detectability of the test. The intraabdominal carcinomatosis described partially mimics the growth characteristics of human ovarian cancer and maintains the expression of some antigenic markers associated with epithelial tumors of the ovary and may therefore be useful in devising immunodiagnostic and/or immunotherapeutic strategies for ovarian carcinoma.