Isolation of cDNA and genomic DNA clones encoding type II collagen.

A cDNA library constructed from total chick embryo RNA was screened with an enriched fraction of type II collagen mRNA. Two overlapping cDNA clones were characterized and shown to encode the COOH propeptide of type II collagen. In addition, a type II collagen clone was isolated from a Charon 4A library of chick genomic fragments. Definitive identification of the clones was based on DNA sequence analysis. The 3' end of the type II collagen gene appears to be similar to that of other interstitial collagen genes. Northern hybridization data indicates that there is a marked decrease in type II collagen mRNA levels in chondrocytes treated with the dedifferentiating agent 5-bromodeoxyuridine. The major type II collagen mRNA species is 5300 bases long, similar to that of other interstitial collagen RNAs.     

Oviposition behaviour and host colony size discrimination in Episyrphus balteatus (Diptera: Syrphidae)

Three bioassays were used to examine the oviposition behaviour of the hoverfly, Episyrphus balteatus (Degeer) in which various stimuli purported to influence host assessment and choice were tested. Episyrphus balteatus failed to exhibit enhanced behavioural responses, in terms of approaches and landings, to artificial leaves with the highest numbers of aphids, suggesting that females are merely responding to the colour of the artificial leaves. A density-dependent oviposition response was reported in a second bioassay using whole bean plants, although there was an asymptotic relationship. Syrphid responses, which were measured by oviposition over a five-day period, were greatest towards those plants with the highest number of aphids. In a final series of trials, gravid female E. balteatus showed a behavioural preference for filter papers treated with the greatest honeydew concentrations (0.26 mg microl(-1) honeydew). More time was spent in the treated areas and syrphids demonstrated more proboscis and ovipositor extensions in these treatments. These bioassays provided an opportunity to isolate some of the individual components of decision-making by female E. balteatus during egg-laying behaviour. A greater understanding of natural enemy behaviour is essential before enhanced control of pest populations in the field can be established.     

Heterophylly in the yellow waterlily, Nuphar variegata (Nymphaeaceae): effects of [CO2], natural sediment type, and water depth

We transplanted Nuphar variegata with submersed leaves only into natural lake sediments in pH-, [CO(2)]-, depth-, and temperature-controlled greenhouse tanks to test the hypotheses that more fertile sediment, lower free [CO(2)], and shallower depth would all stimulate the development of floating leaves. Sediment higher in porewater [NH(4)(+)] favored floating leaf development. Low CO(2)-grown plants initiated floating leaf development significantly earlier than high CO(2)-grown plants, which produced significantly more submersed leaves and fewer floating leaves. Mean floating leaf biomass was significantly greater than mean submersed leaf biomass but was not influenced by CO(2) enrichment, whereas mean submersed leaf biomass increased 88% at high [CO(2)]. At the shallower depth (35 cm), floating leaves required 50% less biomass investment per leaf than at 70 cm, and a significantly greater proportion of plants had floating leaves (70 vs. 23-43% at 35 vs. 70 cm, respectively) for the last three of the eight leaf censuses. Sediment type, water depth, and especially free [CO(2)] all can influence leaf morphogenesis in Nuphar variegata, and the development of more and larger submersed leaves with CO(2) enrichment favors the exploitation of high [CO(2)] when it is present in the water column.     

The PATHWAYS Hospital Project

In 1995, the Hospital Ethics Committee Consortium organized by Midwest Bioethics Center created the PATHWAYS to Patient-Centered Palliative Care: A Community Approach--a guideline document, or "how to" manual for hospitals that want to improve care of the seriously ill and dying. Following the publication and wide dissemination of this manual, the Center began to implement strategies to produce positive change in the way hospitals respond to dying persons and their families. Spurred by the same desire to alter hospital culture through improved care of the dying, eleven hospitals collaborated with the Center to form the PATHWAYS Hospital Project.     

Longliners,black-browed albatross mortality and bait scavenging in Falkland Island waters: what is the relationship?

The rate of foraging attempts by black–browed albatross on baited hooks during Spanish-system (demersal) longline-setting operations, and a range of environmental and operational variables were used to investigate the relationship between their foraging behaviour and their mortality level. Logistic regression highlighted that a complex range of environmental and operational variables and black-browed albatross abundance combined to determine their mortality level. Our results suggest that, examined over a relatively short time period with minimal environmental variation, the rate of black-browed albatross foraging attempts during line-setting significantly affects their level of mortality. However, as a range of variables influence mortality, until targeted experimental studies are conducted, we suggest that caution should be exercised when using the rate of black-browed albatross foraging attempts as an index of their mortality.     

Sequence-specific potentiation of topoisomerase II inhibitors by the histone deacetylase inhibitor suberoylanilide hydroxamic acid

Acetylation of histones leads to conformational changes of DNA. We have previously shown that the histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA), induced cell cycle arrest, differentiation, and apoptosis. In addition to their antitumor effects as single agents, HDAC inhibitors may cause conformational changes in the chromatin, rendering the DNA more vulnerable to DNA damaging agents. We examined the effects of SAHA on cell death induced by topo II inhibitors in breast cancer cell lines. Topo II inhibitors stabilize the topo II-DNA complex, resulting in DNA damage. Treatment of cells with SAHA promoted chromatin decondensation associated with increased nuclear concentration and DNA binding of the topo II inhibitor and subsequent potentiation of DNA damage. While SAHA-induced histone hyperacetylation occurred as early as 4 h, chromatin decondensation was most profound at 48 h. SAHA-induced potentiation of topo II inhibitors was sequence-specific. Pre-exposure of cells to SAHA for 48 h was synergistic, whereas shorter pre-exposure periods abrogated synergy and exposure of cells to SAHA after the topo II inhibitor resulted in antagonistic effects. Synergy was not observed in cells with depleted topo II levels. These effects were not limited to specific types of topo II inhibitors. We propose that SAHA significantly potentiates the DNA damage induced by topo II inhibitors; however, synergy is dependent on the sequence of drug administration and the expression of the target. These findings may impact the clinical development of combining HDAC inhibitors with DNA damaging agents.     

Comparison of the epidemiology, drug resistance mechanisms, and virulence of Candida dubliniensis and Candida albicans

Candida dubliniensis is a pathogenic yeast species that was first identified as a distinct taxon in 1995. Epidemiological studies have shown that C. dubliniensis is prevalent throughout the world and that it is primarily associated with oral carriage and oropharyngeal infections in human immunodeficiency virus (HIV)-infected and acquired immune deficiency syndrome (AIDS) patients. However, unlike Candida albicans, C. dubliniensis is rarely found in the oral microflora of normal healthy individuals and is responsible for as few as 2% of cases of candidemia (compared to approximately 65% for C. albicans). The vast majority of C. dubliniensis isolates identified to date are susceptible to all of the commonly used antifungal agents, however, reduced susceptibility to azole drugs has been observed in clinical isolates and can be readily induced in vitro. The primary mechanism of fluconazole resistance in C. dubliniensis has been shown to be overexpression of the major facilitator efflux pump Mdr1p. It has also been observed that a large number of C. dubliniensis strains express a non-functional truncated form of Cdr1p, and it has been demonstrated that this protein does not play a significant role in fluconazole resistance in the majority of strains examined to date. Data from a limited number of infection models reflect findings from epidemiological studies and suggest that C. dubliniensis is less pathogenic than C. albicans. The reasons for the reduced virulence of C. dubliniensis are not clear as it has been shown that the two species express a similar range of virulence factors. However, although C. dubliniensis produces hyphae, it appears that the conditions and dynamics of induction may differ from those in C. albicans. In addition, C. dubliniensis is less tolerant of environmental stresses such as elevated temperature and NaCl and H(2)O(2) concentration, suggesting that C. albicans may have a competitive advantage when colonising and causing infection in the human body. It is our hypothesis that a genomic comparison between these two closely-related species will help to identify virulence factors responsible for the far greater virulence of C. albicans and possibly identify factors that are specifically implicated in either superficial or systemic candidal infections.     

Nanotechnology and tumor imaging: seizing an opportunity

Nanoparticles, labeled with a signaling moiety for in vivo imaging, and one or more ligands for molecularly targeted specificity, hold considerable promise in oncology. Nanoparticles can serve as modular platforms, from which a wide variety of highly sensitive and specific imaging agents can be created. For example, many hundreds or thousands of atoms that provide imaging signals, such as radioisotopes, lanthanides, or fluorophores, can be attached to each nanoparticle, to form imaging agents that would provide higher sensitivity that can be obtained from agents based on small molecules. Similarly, many copies of targeted ligands can be attached to nanoparticles to markedly increase specific binding. Drugs or therapeutic isotopes can be added to create multifunctional nanoparticles. Appropriately labeled and targeted nanoparticles could lead to a paradigm change in which cancer detection, diagnosis, and therapy are combined in a single molecular complex.     

Aryl tetrahydropyridine inhibitors of farnesyltransferase: bioavailable analogues with improved cellular potency

Inhibitors of farnesyltransferase are effective against a variety of tumors in mouse models of cancer. Clinical trials to evaluate these agents in humans are ongoing. In our effort to develop new farnesyltransferase inhibitors, we have discovered bioavailable aryl tetrahydropyridines that are potent in cell culture. The design, synthesis, SAR and biological properties of these compounds will be discussed.