Long term comparative evaluation of two types of absorbable meshes in partial abdominal wall defects: an experimental study in rabbits.

PURPOSE: Synthetic prosthetic materials that are fully absorbable seek to reduce the host foreign body reaction and promote host tissue regeneration. This preclinical trial was designed to analyse, in the long term, the behaviour of two prosthetic meshes, one synthetic and one composed of porcine collagen, in abdominal wall reconstruction. METHODS: Partial defects were created in the abdominal walls of New Zealand rabbits and repaired using a synthetic absorbable mesh (Phasix™) or a non-crosslinked collagen bioprosthesis (Protexa™). After 3, 6, 12 and 18 months, specimens were recovered for light microscopy and collagen expression analysis to examine new host tissue incorporation, macrophage response and biomechanical strength. RESULTS: Both materials showed good host tissue incorporation in line with their spatial structure. At 18 months postimplant, Protexa™ was highly reabsorbed while the biodegradation of Phasix™ was still incomplete. Collagenization of both materials was good. Macrophage counts steadily decreased over time in response to Phasix™, yet persisted in the collagen meshes. At 18 months, zones of loose tissue were observed at the implant site in the absence of herniation in both implant types. The stress-stretch behaviour of Phasix™ implants decreased over time, being more pronounced during the period of 12-18 months. Nevertheless, the abdominal wall repaired with Protexa™ became stiffer over time. CONCLUSION: Eighteen months after the implant both materials showed good compatibility but the biodegradation of Phasix™ and Protexa™ was incomplete. No signs of hernia were observed at 18 months with the stress-stretch relations being similar for both implants, regardless of the more compliant abdominal wall repaired with Protexa™ at short term.

Experimental study on the use of a chlorhexidine-loaded carboxymethylcellulose gel as antibacterial coating for hernia repair meshes.

PURPOSE: Biomaterials with an antimicrobial coating could avoid mesh-associated infection following hernia repair. This study assesses the use of a chlorhexidine-loaded carboxymethylcellulose gel in a model of Staphylococcus aureus mesh infection. METHODS: A 1% carboxymethylcellulose gel containing 0.05% chlorhexidine was prepared and tested in vitro and in vivo. The in vitro tests were antibacterial activity (S. aureus; agar diffusion test) and gel cytotoxicity compared to aqueous 0.05% chlorhexidine (fibroblasts; alamarBlue). For the in vivo study, partial abdominal wall defects (5 × 2 cm) were created in New Zealand white rabbits (n = 15) and inoculated with 0.25 mL of S. aureus (106 CFU/mL). Defects were repaired with a lightweight polypropylene mesh (Optilene) without coating (n = 3) or coated with a carboxymethylcellulose gel (n = 6) or chlorhexidine-loaded carboxymethylcellulose gel (n = 6). Fourteen days after surgery, bacterial adhesion to the implant (sonication, immunohistochemistry), host tissue incorporation (light microscopy) and macrophage reaction (immunohistochemistry) were examined. RESULTS: Carboxymethylcellulose significantly reduced the toxicity of chlorhexidine (p < 0.001) without limiting its antibacterial activity. While control and gel-coated implants were intensely contaminated, the chlorhexidine-gel-coated meshes showed a bacteria-free surface, and only one specimen showed infection signs. The macrophage reaction in this last group was reduced compared to the control (p < 0.05) and gel groups. CONCLUSIONS: When incorporated in the carboxymethylcellulose gel, chlorhexidine showed reduced toxicity yet maintained its bactericidal effect at the surgery site. Our findings suggest that this antibacterial gel-coated polypropylene meshes for hernia repair prevent bacterial adhesion to the mesh surface and have no detrimental effects on wound repair.

Helicobacter pylori inactivation and virulence gene damage using a supported sensitiser for photodynamic therapy.

About half of the world's population is currently infected with Helicobacter pylori, which is involved in the development of several gastro-duodenal pathologies. The increasing number of antibiotic resistance reduces the effectiveness of the first-line therapy, so new strategies to improve the H. pylori eradication rates are needed. Antimicrobial Photodynamic Therapy (APDT) benefits from photogenerated reactive oxygen species, such as singlet oxygen, which inactivate microorganisms by means of photosensitising dyes and visible light. Therefore, it could be a suitable alternative for H. pylori eradication in the gastro-duodenal tract, particularly in patients infected with antibiotic resistant strains. We evaluated APDT against H. pylori, in vitro, using a new photosensitising material (PSM) based on a ruthenium(II) complex covalently bound to micrometric glass beads. Five H. pylori isolates (classified according to cagA genotype, and metronidazole-clarithromycin resistance) were used. Bacteria were mixed with the PSM and incubated in the dark or illuminated by blue light. Aliquots (min 1', 2', 5', 15' and 30') were cultured and colonies were counted after 2-3 days. A 99.99999% decrease was detected in the number of colonies in the irradiated wells where the bacterium was mixed with the PSM, compared to non-illuminated wells or with irradiated wells without PSM. It was also confirmed that DNA is a molecular target for oxidant species released during APDT (evaluated by alkaline gel electrophoresis after endonuclease III incubation, ureC and cagA RT-PCR, and bacterial fingerprint). Results were independent of cagA gene and antibiotic resistances.

Cytokines - their pathogenic and therapeutic role in chronic viral hepatitis.

Cytokines make up a network of molecules involved in the regulation of immune response and organ functional homeostasis. Cytokines coordinate both physiological and pathological processes occurring in the liver during viral infection, including infection control, inflammation, regeneration, and fibrosis. Hepatitis B and hepatitis C viruses interfere with the complex cytokine network brought about by the immune system and liver cells in order to prevent an effective immune response, capable of viral control. This situation leads to intrahepatic sequestration of nonspecific inflammatory infiltrates that release proinflammatory cytokines, which in turn favor chronic inflammation and fibrosis. The therapeutical administration of cytokines such as interferon alpha may result in viral clearance during persistent infection, and revert this process.

Cytokines – their pathogenic and therapeutic role in chronic viral hepatitis

Cytokines make up a network of molecules involved in the regulationof immune response and organ functional homeostasis. Cytokinescoordinate both physiological and pathological processesoccurring in the liver during viral infection, including infection control,inflammation, regeneration, and fibrosis. Hepatitis B and hepatitisC viruses interfere with the complex cytokine networkbrought about by the immune system and liver cells in order to preventan effective immune response, capable of viral control. This situationleads to intrahepatic sequestration of nonspecific inflammatoryinfiltrates that release proinflammatory cytokines, which in turnfavor chronic inflammation and fibrosis. The therapeutical administrationof cytokines such as interferon alpha may result in viral clearanceduring persistent infection, and revert this process(AU)

Regulación de la expresión del co-receptor CCR5 en sujetos con virus de la inmunodeficiencia humana / Expression regulation of CCR5 co-receptor in human immunodeficiency virus subjects

Objetivos Estudiar la expresión diferencial del co-receptor CCR5, en superficie e intracelularmente, en T4 y T8 de pacientes VIH frente a controles. Evaluar causas y mecanismos de regulación de esa expresión en sujetos VIH. Pacientes Se analizaron muestras de 11 controles y 14 de VIH en terapia antirretroviral. Resultados La expresión de superficie del CCR5 en T4 y T8 depacientes VIH disminuyó un 38 y 53% respectivamentefr ente a controles, observándose diferencias estadísticamente significativas. El CCR5 intracelular en T8 fue similar al de controles, sinembargo, en T4 de VIH la proteína intracelular fue más abundante y, como consecuencia, la cantidad total de CCR5 similar a la total de controles. Conclusiones Existe una regulación diferencial en la expresión del CCR5 en T4 y T8 de VIH en relación a controles. En ambas subpoblaciones, la expresión de superficie se halla disminuida, hecho que parece responder a razones diferentes: en T4 se produce internalización de CCR5 quizá como consecuencia de ser arrastrado al interior celular en el proceso de infección por el virus, pero su expresión global es similar a la de controles, en T8 en cambio, no hay internalización sino regulación negativa del receptor en superficie, probablemente consecuencia de la sobreexpresión de interleuquinas ligando del co-receptor que se observaen estos pacientes. Son necesarios estudios que evalúen y expliquen el diferente comportamiento de estas subpoblaciones en la regulación del CCR5 para ampliar el conocimiento sobre la fisiopatología de la enfermedad y facilitar la elección de terapias más efectivas y menos agresiva

Objectives To study the differential expression of CCR5 co-receptor, in surface and intracellularly, in T4 and T8 cells of HIV patients respect to controls. To evaluate causes and mechanisms of that expression regulation in HIV subjects. Patients II controls and 14 HN patients with antirretroviral therapy were studied. Results CCR5 surface expression of HN, both in T4 and in T8, was diminished 38 and 53% respectively respect to controls with significant differences. CCR5 intracellular in T8 was similar to controls, never the less, the intracellular protein in T4 was more abundant and as a consequence, the total amount of CCR5 was similar to the total (surface+intracellular)in controls. Conclusions It exists a diferential regulation in the expression of CCR5 in T4 and T8 of HIV regard to controls. In both subpopulations, the surface expression is diminished,lact that seems to respond to different reasons: In T4 was produced a CCR5 internalization, perhaps as aresult 01 being dragged to the citosol in the virus infection process, but its global expression was similar to controls. However, in T8 there was not internalization but negative regulation of surface receptor, probably due to the sobreexpression of interleukins binding of the co-receptor, what is characteristic in these patients. They are necessary studies that evaluate and explain the different behavior of these subpopulations in the CCR5 regulation to extend the knowledge on the physiopathology of the disease and to facilitate the election of more effective and less aggressive therapies

Flow cytometric analysis of the in situ hybridization of cyclooxygenase isoforms in mesangial cells treated with cyclosporine A.

BACKGROUND: Cyclosporine A increases oxidative stress in kidney and we hypothesized that cyclooxygenase (COX) may be involved in this effect. MATERIAL AND METHODS: Mesangial cells of Cyclosporine A-treated (4, 7 or 10 days) rats were obtained to evaluate mRNA expression of COX-isoforms (COX-1, constitutive and COX-2, inducible) by "in situ" hybridization. Probes were labelled using "Gene Image Random Prime Labelling Protocol" and COX expression was measured by flow cytometry. RESULTS AND DISCUSSION: "In situ" hybridization by flow cytometry is an useful method to detect mRNA. We observed an increased COX-2 expression in a time-dependent manner in parallel with Reactive Oxygen Species synthesis. COX-1 expression increased only at 10 days.