Food Restriction and Atherosclerotic Plaque Stabilization

Food restriction is a promising therapy for many age-associated pathologies as it stimulates the health-supportive mechanism autophagy. Because atherosclerosis is an inflammatory, age-related disease, dietary modification can be an important strategy in preventing atherosclerotic plaque development. A cholesterol-supplemented diet, used to induce plaque formation in rabbits, induces a pronounced hypercholesterolemia, which can be reversed after 4 weeks of normal diet. However, food restriction induces a further increase in circulating LDL cholesterol. These elevated cholesterol levels are associated with the induction of autophagy. Although neither a short-term normal diet nor food restriction alters plaque size, rabbits fed a normal diet show signs of increased plaque stability such as elevated collagen content and decreased expression of vascular cell adhesion molecule (VCAM)-1. Surprisingly, these favorable effects are not present after 4 weeks of food restriction. On the contrary, atherosclerotic plaques of food-restricted rabbits displayed enhanced apoptosis, a process known to further undermine plaque stability. In conclusion, severe short-term food restriction in rabbits prevents stabilization of atherosclerotic plaques as observed after regular cholesterol withdrawal via a normal diet

Comparison of Apoptosis Detection Markers Combined with Macrophage Immunostaining to Study Phagocytosis of Apoptotic Cells in Situ

Efficient phagocytosis of cells undergoing apoptosis by macrophages is important to prevent immunological responses and development of chronic inflammatory disorders such as systemic lupus erythematosus, cystic fibrosis and atherosclerosis. To study phagocytosis of apoptotic cells (AC) by macrophages in tissue, we validated different apoptosis markers (DNA fragmentation, caspase-3 activation and cleavage of its substrate poly(ADP-ribose)polymerase-1) in combination with macrophage immunostaining. Human tonsils were used as a model because they show a high apoptosis frequency under physiological conditions as well as efficient phagocytosis of AC by macrophages. On the other hand, advanced human atherosclerotic plaques were examined since plaques show severely impaired phagocytosis of AC. Our results demonstrate that the presence of non-phagocytized terminal deoxynucleotidyl transferase end labelling (TUNEL)-positive AC represents a suitable marker of poor phagocytosis by macrophages in situ. Other markers for apoptosis, such as cleavage of caspase-3 or PARP-1, should not be used to assess phagocytosis efficiency, because activation of the caspase cascade and cleavage of their substrates can occur in AC when they have not yet been phagocytized by macrophages

Silicone adhesive multilayer foam dressings as adjuvant prophylactic therapy to prevent hospital-acquired pressure ulcers : a pragmatic noncommercial multicentre randomized open-label parallel-group medical device trial

Background: Silicone adhesive multilayer foam dressings are used as adjuvant therapy to prevent hospital‐acquired pressure ulcers (PUs). Objectives: Determine if silicone foam dressings in addition to standard prevention reduce PU incidence category 2 or worse compared to standard prevention alone. Methods: Multicentre, randomised controlled, medical device trial conducted in eight Belgian hospitals. At risk adult patients were centrally randomised (n=1633) to study groups based on a 1:1:1 allocation: experimental group 1 (n=542) and 2 (n=545) ‐ pooled as the treatment group ‐ and the control group (n=546). Experimental groups received PU prevention according to hospital protocol, and a silicone foam dressing on these body sites. The control group received standard of care. The primary endpoint was the incidence of a new PU category 2 or worse at these body sites. Results: In the intention‐to‐treat population (n=1605); 4.0% of patients developed PUs category 2 or worse in the treatment group and 6.3% in the control group (RR=0.64, 95% CI 0.41 to 0.99, P=0.04). Sacral PUs were observed in 2.8% and 4.8% of the patients in the treatment group and the control group, respectively (RR=0.59, 95% CI 0.35 to 0.98, P=0.04). Heel PUs occurred in 1.4% and 1.9% of patients in the treatment and control group respectively (RR=0.76, 95% CI 0.34 to 1.68, P=0.49). Conclusions: Silicone foam dressings reduce the incidence of PUs category 2 or worse in hospitalised at‐risk patients when used in addition to standard of care. Results show a decrease for sacrum, but no statistical difference for heel/trochanter areas

A Novel Substrate-Based HIV-1 Protease Inhibitor Drug Resistance Mechanism

BACKGROUND: HIV protease inhibitor (PI) therapy results in the rapid selection of drug resistant viral variants harbouring one or two substitutions in the viral protease. To combat PI resistance development, two approaches have been developed. The first is to increase the level of PI in the plasma of the patient, and the second is to develop novel PI with high potency against the known PI-resistant HIV protease variants. Both approaches share the requirement for a considerable increase in the number of protease mutations to lead to clinical resistance, thereby increasing the genetic barrier. We investigated whether HIV could yet again find a way to become less susceptible to these novel inhibitors. METHODS AND FINDINGS: We have performed in vitro selection experiments using a novel PI with an increased genetic barrier (RO033-4649) and demonstrated selection of three viruses 4- to 8-fold resistant to all PI compared to wild type. These PI-resistant viruses did not have a single substitution in the viral protease. Full genomic sequencing revealed the presence of NC/p1 cleavage site substitutions in the viral Gag polyprotein (K436E and/or I437T/V) in all three resistant viruses. These changes, when introduced in a reference strain, conferred PI resistance. The mechanism leading to PI resistance is enhancement of the processing efficiency of the altered substrate by wild-type protease. Analysis of genotypic and phenotypic resistance profiles of 28,000 clinical isolates demonstrated the presence of these NC/p1 cleavage site mutations in some clinical samples (codon 431 substitutions in 13%, codon 436 substitutions in 8%, and codon 437 substitutions in 10%). Moreover, these cleavage site substitutions were highly significantly associated with reduced susceptibility to PI in clinical isolates lacking primary protease mutations. Furthermore, we used data from a clinical trial (NARVAL, ANRS 088) to demonstrate that these NC/p1 cleavage site changes are associated with virological failure during PI therapy. CONCLUSIONS: HIV can use an alternative mechanism to become resistant to PI by changing the substrate instead of the protease. Further studies are required to determine to what extent cleavage site mutations may explain virological failure during PI therapy