Blood flow dynamics after photodynamic therapy with verteporfin in the RIF-1 tumor

In the present study, the effects of photodynamic therapy (PDT) with verteporfin on tumor blood flow and tumor regrowth were compared as verteporfin distributed in different compartments within the RIF-1 tumor. Tissue distribution of verteporfin was examined by fluorescence microscopy, and blood flow measurements were taken with a laser Doppler system. It was found that, at 15 min after drug administration, when verteporfin was mainly confined within the vasculature, PDT induced a complete arrest of blood flow by 6 h after treatment. PDT treatment at a longer drug-light interval (3 h), which allowed the drug to diffuse to the tumor interstitium, caused significantly less flow decrease, only to 50% of the initial flow in 6 h. A histological study and Hoechst 33342 staining of functional tumor vasculature confirmed the primary vascular damage and the decrease in tumor perfusion. The regrowth rate of tumors treated with 15-min interval PDT was 64% of that of the control group. However, when tumors were treated with 3-h interval PDT, the regrowth rate was not significantly different from that of the control, indicating that only the 15-min interval PDT caused serious damage to the tumor vascular bed. These results support the hypothesis that temporal pharmacokinetic changes in the distribution of the photosensitizer between the tumor parenchyma and blood vessels can significantly alter the tumor target of PDT.     

Shigella dysenteriae type 1-specific bacteriophage from environmental waters in Bangladesh

Shigella dysenteriae type 1 is the causative agent of the most severe form of bacillary dysentery, which occurs as epidemics in many developing countries. We isolated a bacteriophage from surface water samples from Bangladesh that specifically lyses strains of S. dysenteriae type 1. This phage, designated SF-9, belongs to the Podoviridae family and has a 41-kb double-stranded DNA genome. Further screening of water samples for the prevalence of the phage revealed 9 of 71 (12.6%) water samples which were positive for the phage. These water samples were also positive in PCR assays for one or more S. dysenteriae type 1-specific genes, including ipaBCD and stx1, and live S. dysenteriae type 1 was isolated from three phage-positive samples. The results of this study suggest that phage SF-9 may have epidemiological applications in tracing the presence of S. dysenteriae type 1 in environmental waters.     

Iridoid and bisiridoid glycosides from Globularia cordifolia

From the methanolic extract of the underground parts of Globularia cordifolia, a new iridoid glycoside, 5-hydroxydavisioside (1) and a new bisiridoid glycoside, globuloside C (2) were isolated along with six known iridoid glycosides, aucubin, melampyroside, monomelittoside, globularifolin, alpinoside and asperuloside. The structures of the isolates were established by 1D and 2D NMR spectroscopy in combination with IR, UV and MS analyses.     

Expression patterns of two putative odorant-binding proteins in the olfactory organs of Drosophila melanogaster have different implications for their functions

The aqueous medium bathing the dendrites of olfactory neurons contains high concentrations of odorant-binding proteins (OBPs) whose role is still unclear. OBPs may facilitate interactions between odorants and their membrane-bound receptors, perhaps by increasing the water solubility of hydrophobic molecules. Alternatively, OBPs may be involved in the inactivation of odorants and other volatile molecules, preventing desensitization and/or protecting olfactory neurons from toxic chemicals. We report here novel features of the localization of two putative OBPs, PBPRP2 and PBPRP5, that have important and different implications for their role in olfaction. Unlike several other putative OBPs of Drosophila melanogaster that are only found in adult olfactory organs, PBPRP5 is also expressed in the larval olfactory organs, suggesting that it plays a common role in olfaction at both stages. In the adult, PBPRP5 expression is restricted to the sensillum lymph that bathes the olfactory dendrites of a subset of olfactory hairs, the basiconic sensilla. Since individual basiconic sensilla differ in olfactory specificity, PBPRP5 may be able to bind to and mediate olfactory responses to a wide range of odorants. In contrast, PBPRP2 is present in the space immediately below the antennal cuticle and in the outer cavity of approximately 30% of the double-walled coeloconic sensilla on the antennal surface. In neither case is PBPRP2 in contact with the dendritic membranes of olfactory neurons, making a carrier function unlikely for this protein. Instead, PBPRP2 may act as a sink, binding to odorants and other volatile chemicals and limiting their interactions with olfactory neurons.     

Counterpoint. Cancer vaccines: single-epitope anti-idiotype vaccine versus multiple-epitope antigen vaccine

Anti-idiotype (Id) vaccine therapy has been tested and shown to be effective, in several animal models, for triggering the immune system to induce specific and protective immunity against bacterial, viral and parasitic infections. The administration of anti-Id antibodies as surrogate tumor-associated antigens (TAA) also represents another potential application of the concept of the Id network. Limited experience in human trials using anti-Id to stimulate immunity against tumors has shown promising results. In this “counterpoint” article, we discuss our own findings showing the potential of anti-Id antibody vaccines to be novel therapeutic approaches to various human cancers and also discuss where anti-Id vaccines may perform better than traditional multiple-epitope antigen vaccines. Received: 27 December 1999 / Accepted: 27 January 2000     

A direct interaction between proliferating cell nuclear antigen (PCNA) and Cdk2 targets PCNA-interacting proteins for phosphorylation

Proliferating cell nuclear antigen is best known as a DNA polymerase accessory protein but has more recently also been shown to have different functions in important cellular processes such as DNA replication, DNA repair, and cell cycle control. PCNA has been found in quaternary complexes with the cyclin kinase inhibitor p21 and several pairs of cyclin-dependent protein kinases and their regulatory partner, the cyclins. Here we show a direct interaction between PCNA and Cdk2. This interaction involves the regions of the PCNA trimer close to the C termini. We found that PCNA and Cdk2 form a complex together with cyclin A. This ternary PCNA-Cdk2-cyclin A complex was able to phosphorylate the PCNA binding region of the large subunit of replication factor C as well as DNA ligase I. Furthermore, PCNA appears to be a connector between Cdk2 and DNA ligase I and to stimulate phosphorylation of DNA ligase I. Based on our results, we propose the model that PCNA brings Cdk2 to proteins involved in DNA replication and possibly might act as an "adaptor" for Cdk2-cyclin A to PCNA-binding DNA replication proteins.     

Efficient gene transfer to airway epithelium using recombinant Sendai virus

Clinical studies of gene therapy for cystic fibrosis (CF) suggest that the key problem is the efficiency of gene transfer to the airway epithelium. The availability of relevant vector receptors, the transient contact time between vector and epithelium, and the barrier function of airway mucus contribute significantly to this problem. We have recently developed recombinant Sendai virus (SeV) as a new gene transfer agent. Here we show that SeV produces efficient transfection throughout the respiratory tract of both mice and ferrets in vivo, as well as in freshly obtained human nasal epithelial cells in vitro. Gene transfer efficiency was several log orders greater than with cationic liposomes or adenovirus. Even very brief contact time was sufficient to produce this effect, and levels of expression were not significantly reduced by airway mucus. Our investigations suggest that SeV may provide a useful new vector for airway gene transfer.