Quantitation of the tumor-targeting properties of antibody fragments conjugated to cell-permeating HIV-1 TAT peptides

Human monoclonal antibodies are promising agents for the development of more selective anticancer therapeutics. However, the tumor-targeting efficiency of most anticancer antibodies is severely limited by their poor penetration into the tumor mass. Recent studies have shown that a peptide derived from the HIV TAT protein could improve the distribution of cytoplasmic reporter proteins when administered systemically as fusion proteins or cross-linked chimeras. In this article, we tested by quantitative biodistribtution analysis whether conjugation to TAT peptides could improve the tumor targeting properties of scFv(L19)-Cys: an engineered human antibody fragment specific for the ED-B domain of fibronectin, a marker located in the modified extracellular matrix surrounding tumor neovasculature. Our results show that TAT peptides, consisting either of L-amino acids or D-amino acids, can efficiently transduce target cells when conjugated to fluorophores and/or antibody fragments, suggesting a receptor-independent cell entry mechanism. However, conjugation of scFv(L19)-Cys to TAT peptides resulted in a severely reduced tumor targeting performance compared to the unconjugated antibody, as measured in murine F9 teratocarcinoma-bearing mice, after intravenous injection of the radiolabeled antibody preparations. Our results outline the usefulness of TAT peptides for the efficient in vitro transduction of cells with globular proteins. In particular, the use of TAT peptides composed of D-amino acids may significantly reduce proteolytic degradation. At the same time, the poor biodistribution properties of antibody-TAT conjugates cast doubts over the applicability of this methodology for the delivery of biopharmaceuticals in vivo.     

Chromosomal defects in 34 male homosexuals,half of them with HIV antibodies

Most of the research about viral interactions with human chromosomes was done during the sixties and early seventies and very few was performed after the human immunodeficiency virus (HIV) appearance as an epidemic in the eighties. The objective of this work was to estimate if particular chromosomal changes follow the infection of homosexual males by HIV and to determine if the lifestyle, habits, sexual practices, of our sample of male homosexuals predisposes them to chromosomal abnormalities at a higher rate than the background level of cytogenetic damage the general population has. This was a double blinded case-control study, 17 individuals positive for HIV antibodies (HIV+) detected by enzyme-linked immunosorbent assay (ELISA) and confirmed by western blot (WB) were the cases, and 17 individuals negative for HIV antibodies (HIV-) the controls. These men were a very homogeneous population in terms of age, social status, lifestyles, drug abuse, sexual practices and education. Blood was collected between September 1988 and October 1989. Fresh whole blood was cultured in duplicate for 72 hr. Cell harvest followed conventional methods. Once all cell cultures were gathered, the tubes were picked up at random and air dried chromosome preparations were trypsin-giemsa banded (GTG) after overnight incubation at 60 C degrees. The percentage of gaps and breaks these men had was not different from the reported for the general population, nor were there significant difference among both groups (O.R. = 1.8) in items of amount of chromosomal fragility. The distinction among them was at the level of the specific chromosomal sites where the gaps and breaks located, being sites at 2p21 and at 3p21 four times more frequent among HIV+. These probably represent viral modification sites on chromosomes which are known to look like non-staining gaps which are caused by the virus or viral products. This presumption is supported by an earlier report of repeated breaks at 3p21.1, in fact this was the most common lesion site in this study of chromosomal aberrations of male homosexuals and the authors even considered the probability of "a new type of chromosome marker". Furthermore, years later the CKR5 structural gene was mapped to human chromosome 3p21. This gene codes for the chemokine receptor 5 (CKR5) protein which serves as a secondary receptor on CD4+ T lymphocytes for certain strains of HIV-1. It is possible that this gene was being transcribed in HIV+ men and the consequent "staggering" of DNA contributed to the production of gaps and breaks at 3p21.     

Culturable Microbial Diversity and the Impact of Tourism in Kartchner Caverns,Arizona

Kartchner Caverns in Benson, AZ, was opened for tourism in 1999 after a careful development protocol that was designed to maintain predevelopment conditions. As a part of an ongoing effort to determine the impact of humans on this limestone cave, samples were collected from cave rock surfaces along the cave trail traveled daily by tour groups (200,000 visitors year^–1) and compared to samples taken from areas designated as having medium (30–40 visitors year^–1) and low (2–3 visitors year^–1) levels of human exposure. Samples were also taken from fiberglass moldings installed during cave development. Culturable bacteria were recovered from these samples and 90 unique isolates were identified by using 16S rRNA polymerase chain reaction and sequencing. Diversity generally decreased as human impact increased leading to the isolation of 32, 27, and 22 strains from the low, medium, and high impact areas, respectively. The degree of human impact was also reflected in the phylogeny of the isolates recovered. Although most isolates fell into one of three phyla: Actinobacteria, Firmicutes, or Proteobacteria, the Proteobacteria were most abundant along the cave trail (77% of the isolates), while Firmicutes predominated in the low (66%) and medium (52%) impact areas. Although the abundance of Proteobacteria along the cave trail seems to include microbes of environmental rather than of anthropogenic origin, it is likely that their presence is a consequence of increased organic matter availability due to lint and other organics brought in by cave visitors. Monitoring of the cave is still in progress to determine whether these bacterial community changes may impact the future development of cave formations.     

Rescue of Fructose-Induced Metabolic Syndrome by Antibiotics or Faecal Transplantation in a Rat Model of Obesity

A fructose-rich diet can induce metabolic syndrome, a combination of health disorders that increases the risk of diabetes and cardiovascular diseases. Diet is also known to alter the microbial composition of the gut, although it is not clear whether such alteration contributes to the development of metabolic syndrome. The aim of this work was to assess the possible link between the gut microbiota and the development of diet-induced metabolic syndrome in a rat model of obesity. Rats were fed either a standard or high-fructose diet. Groups of fructose-fed rats were treated with either antibiotics or faecal samples from control rats by oral gavage. Body composition, plasma metabolic parameters and markers of tissue oxidative stress were measured in all groups. A 16S DNA-sequencing approach was used to evaluate the bacterial composition of the gut of animals under different diets. The fructose-rich diet induced markers of metabolic syndrome, inflammation and oxidative stress, that were all significantly reduced when the animals were treated with antibiotic or faecal samples. The number of members of two bacterial genera, Coprococcus and Ruminococcus, was increased by the fructose-rich diet and reduced by both antibiotic and faecal treatments, pointing to a correlation between their abundance and the development of the metabolic syndrome. Our data indicate that in rats fed a fructose-rich diet the development of metabolic syndrome is directly correlated with variations of the gut content of specific bacterial taxa.     

Mechanisms of interleukin-6 protection against ischemia-reperfusion injury in rat liver

Numerous animal studies simulating liver injury have demonstrated that interleukin-6 (IL-6) exerts a protective effect. This study was designed to further analyze the molecular mechanisms underlying the protective role of IL-6 in a rat model of liver ischemia/reperfusion injury. We show that IL-6: (i) at high doses reduces cell damage which occurs in ischemic-reperfused liver, while at low doses displays only a limited protective capacity, (ii) anticipates and enhances hepatocyte compensatory proliferation seen in ischemic-reperfused liver also at a low, more pharmacologically acceptable dose, (iii) sustains the acute phase response which is dampened in ischemic-reperfused liver, (iv) strengthens the heat shock-stress response shown by ischemic-reperfused liver and (v) overcomes the dysfunctions of the unfolding protein response found in ischemic-reperfused liver. We also show that IL-6-enhanced STAT3 activation probably plays a crucial role in the potentiation of the different protective pathways activated in ischemic-reperfused liver. Our data confirm that IL-6 is a potential therapeutic in liver injury of different etiologies and reveal novel mechanisms by which IL-6 sustains liver function after ischemia/reperfusion injury.     

Oral Candida colonization in patients with chronic periodontitis. Is there any relationship?

Background

Candida can be implicated in the pathology of chronic periodontitis.

Strategies for PHA production by mixed cultures and renewable waste materials

Production of polyhydroxyalkanoates (PHA) by mixed cultures has been widely studied in the last decade. Storage of PHA by mixed microbial cultures occurs under transient conditions of carbon or oxygen availability, known respectively as aerobic dynamic feeding and anaerobic/aerobic process. In these processes, PHA-accumulating organisms, which are quite diverse in terms of phenotype, are selected by the dynamic operating conditions imposed to the reactor. The stability of these processes during long-time operation and the similarity of the polymer physical/chemical properties to the one produced by pure cultures were demonstrated. This process could be implemented at industrial scale, providing that some technological aspects are solved. This review summarizes the relevant research carried out with mixed cultures for PHA production, with main focus on the use of wastes or industrial surplus as feedstocks. Basic concepts, regarding the metabolism and microbiology, and technological approaches, with emphasis on the kind of feedstock and reactor operating conditions for culture selection and PHA accumulation, are described. Challenges for the process optimization are also discussed.     

Effects of climate change and horticultural use on the spread of naturalized alien garden plants in Europe

Climate warming is supposed to enlarge the area climatically suitable to the naturalization of alien garden plants in temperate regions. However, the effects of a changing climate on the spread of naturalized ornamentals have not been evaluated by spatially and temporarily explicit range modelling at larger scales so far. Here, we assess how climate change and the frequency of cultivation interactively determine the spread of 15 ornamental plants over the 21st century in Europe. We coupled species distribution modelling with simulations of demography and dispersal to predict range dynamics of these species in annual steps across a 250 × 250 m raster of the study area. Models were run under four scenarios of climate warming and six levels of cultivation intensity. Cultivation frequency was implemented as size of the area used for planting a species. Although the area climatically suitable to the 15 species increases, on average, the area predicted to be occupied by them in 2090 shrinks under two of the three climate change scenarios. This contradiction obviously arises from dispersal limitations that were pronounced although we assumed that cultivation is spatially adapting to the changing climate. Cultivation frequency had a much stronger effect on species spread than climate change, and this effect was non‐linear. The area occupied increased sharply from low to moderate levels of cultivation intensity, but levelled off afterwards. Our simulations suggest that climate warming will not necessarily foster the spread of alien garden plants in Europe over the next decades. However, climatically suitable areas do increase and hence an invasion debt is likely accumulating. Restricting cultivation of species can be effective in preventing species spread, irrespective of how the climate develops. However, for being successful, they depend on high levels of compliance to keep propagule pressure at a low level.     

Trophoblasts regulate the placental hematopoietic niche through PDGF-B signaling

The placenta is a hematopoietic organ that supports hematopoietic stem/progenitor cell (HSPC) generation and expansion without promoting differentiation. We identified PDGF-B signaling in trophoblasts as a key component of the unique placental hematopoietic microenvironment that protects HSPCs from premature differentiation. Loss of PDGF-B or its receptor, PDGFRβ, induced definitive erythropoiesis in placental labyrinth vasculature. This was evidenced by accumulation of CFU-Es and actively proliferating definitive erythroblasts that clustered around central macrophages, highly reminiscent of erythropoiesis in the fetal liver. Ectopic erythropoiesis was not due to a requirement of PDGF-B signaling in hematopoietic cells but rather in placental trophoblasts, which upregulated Epo in the absence of PDGF-B signaling. Furthermore, overexpression of hEPO specifically in the trophoblasts in vivo was sufficient to convert the placenta into an erythropoietic organ. These data provide genetic evidence of a signaling pathway that is required to restrict erythroid differentiation to specific anatomical niches during development.