Long-term follow-up on the effects of sodium oxybate on daytime sleepiness and sleep architecture in patients with narcolepsy type 1

INTRODUCTION

Sodium oxybate (SXB) was administered for the first time in 1979 in 16 patients with narcolepsy with cataplexy (NT1) that improved up to 20 months.

AIMS

To evaluate the effect of SXB on daytime sleepiness and sleep architecture by video-polysomnography in a sample of 23 NT1 adult patients (13 men, 10 females) treated up to three years. Additional goal was to study the presence of sleep comorbidities.

PATIENTS AND METHODS

NT1 patients were diagnosed according to International Classification of Sleep Disorders, third edition. We conducted a longitudinal observational study and a video-polysomnography comparing the sleep parameters of patients treated with an initial nocturnal dose of 4.5 g of SXB after six months (FU-1), one year (FU-2) and three years (FU-3) of uninterrupted treatment. Video-polysomnography parameters were analyzed including apnea-hypopnea and periodic leg movements indexes.

RESULTS

Patients were HLA-DQB1*06:02 positive except a familial case. Thirteen patients (56%) discontinued SXB treatment over the three-year of the study. The two-nightly doses has been one of the reason for discontinuing treatment as well as insufficient compliance, mild or severe side effects, comorbidities and pregnancy. We found significant differences at FU-2 in sleep structure with an increased in stage N2 (p < 0.03) and a higher periodic leg movements index (p < 0.01). At FU-3 we found significant differences in sleep structure with an increase in stage N1 (p = 0.03) and in comorbidities (periodic leg movements and apnea-hypopnea indexes). There was not significant change on daytime sleepiness during the study.

CONCLUSIONS

SXB was administered in low-medium doses. Two-nightly doses and sleep fragmentation linked to sleep comorbidities at long-term lead to drug withdrawal.

Potentially inappropriate medications in older adults living with HIV

OBJECTIVES

We assessed the prevalence of potentially inappropriate medication (PIM) among older (≥ 65 years) people living with HIV (O-PLWH) in the region of Madrid.

METHODS

We analysed the dispensation registry of community and hospital pharmacies from the Madrid Regional Health Service (SERMAS) for the period between 1 January and 30 June 2017, looking specifically at PIMs according to the 2019 Beers criteria. Co-medications were classified according to the Anatomical Therapeutic Chemical (ATC) classification system.

RESULTS

A total of 6 636 451 individuals received medications. Of these individuals, 22 945 received antiretrovirals (ARVs), and of these 1292 were O-PLWH. Overall, 1135 (87.8%) O-PLWH were taking at least one co-medication, and polypharmacy (at least five co-medications) was observed in 852 individuals (65.9%). A PIM was identified in 482 (37.3%) O-PLWH. Factors independently associated with PIM were polypharmacy [adjusted odds ratio (aOR) 7.08; 95% confidence interval (CI) 5.16-9.72] and female sex (aOR 1.75; 95% CI 1.30-2.35). The distribution of PIMs according to ATC drug class were nervous system drugs (n = 369; 28.6%), musculoskeletal system drugs (n = 140; 10.8%), gastrointestinal and metabolism drugs (n = 72; 5.6%), cardiovascular drugs (n = 61; 4.7%), respiratory system drugs (n = 13; 1.0%), antineoplastic and immunomodulating drugs (n = 10; 0.8%), and systemic anti-infectives (n = 2; 0.2%). Five drugs accounted for 84.8% of the 482O PLWH with PIMs: lorazepam (38.2%), ibuprofen (18.0%), diazepam (10.2%), metoclopramide (9.9%), and zolpidem (8.5%).

CONCLUSIONS

Prescription of PIMs is highly prevalent in O-PLWH. Consistent with data in uninfected elderly people, the most frequently observed PIMs were benzodiazepines and nonsteroidal anti-inflammatory drugs . Targeted interventions are warranted to reduce inappropriate prescribing and polypharmacy in this vulnerable population.

Changes in Metalloproteinase (MMP-1, MMP-2) Expression in the Proximal Region of the Varicose Saphenous Vein Wall in Young Subjects

Objective:

An evaluation of the proteoglycan perlecan, collagen I and III, and metalloproteinases MMP−1, −2, −3 and −9 was performed to explore the possible relationships between ageing, affected vein region and reactive state of the varicose vein wall.

Methods:

Segments of saphenous vein were obtained from healthy subjects and from those with varicose veins. The vein specimens were subdivided according to subject age (<50/^50) and vein source (distal/proximal).

Results:

The walls of control vein specimens acquired a more collagenous appearance with age. These changes were not accompanied by significant modifications in the immunohistochemical markers used. In specimens from young patients, proximal varicose vein segments showed an increase in MMP-1, MMP-2 and MMP-9 expression. Subjects of more advanced age showed an increase in perlecan expression.

Conclusion:

This increase in MMPs could lead to the acceleration of the final fibrosclerotic process characteristic of the varicose vein wall.

Tissue integration and inflammatory reaction in full-thickness abdominal wall repair using an innovative composite mesh

PURPOSE

When composite meshes are used in abdominal wall repair, seroma formation may persist and delay the desired integration leading to recurrence. This study compares tissue integration and inflammatory response in abdominal wall repair with composites with different absorbable synthetic barriers.

METHODS

Full-thickness defects created in the abdominal wall of rabbits were repaired using polypropylene prosthesis or the following composites: Physiomesh™ (Phy); Ventralight™ (Vent) and "new composite mesh" (Ncm) not yet used clinically in humans. The collected seroma was evaluated for IFN-γ/IL-4 by ELISA. Tissue integration, anti- (IL-13/TGFβ-1/IL-10/IL-4) and pro-inflammatory (TNF-α/IL-6/IFN-γ/VEGF) cytokine mRNA expression and TGFβ/VEGF immunolabeling were evaluated at 14 and 90 days post-implant.

RESULTS

Seroma was observed in 10 of 12 Phy/Vent and 4 of 12 Ncm. Wound fluid IFN-γ showed a time-dependent significant increase in Vent and tendency to decrease in Ncm, while all composites exhibited IL-4 upward trend. Prostheses were fully infiltrated by an organized connective tissue at end time although the area had shown prior seroma. A stable mesothelium was developed, except in adhesion areas. Vent/Phy displayed a significant increase in TNF-α/IFN-γ-mRNA over time. Significant decrease in VEGF mRNA was observed in Phy/Ncm, while a significant increase of TGFβ-1 mRNA was evident in all composites over time. Ncm exhibited the highest TGFβ protein expression area at short term and the greatest percentage of VEGF positive vessels at end time.

CONCLUSION

Ncm could be an appropriate candidate to improve clinical outcome showing the lower development of seroma and optimal tissue integration with minimal pro-inflammatory cytokine response over time and consistent pro-wound healing cytokine expression.

Bacterial adhesion to biological versus polymer prosthetic materials used in abdominal wall defect repair: do these meshes show any differences in vitro?

PURPOSE

Although clinical data suggest the similar performance of collagen-based biological prosthetic materials to some polymer materials, the use of a biomesh for abdominal hernia repair in a setting of infection is controversial. This in vitro study compares the adhesion of two Staphylococcus strains to polymer and biological meshes.

METHODS

Sterile fragments of Optilene(®) (Op), Surgipro™ (Surg), Preclude(®) (Precl), TIGR(®) (TIGR), Bio-A(®) (BioA), Permacol™ (Perm), Surgisis(®) (SIS), and Tutomesh(®) (Tuto) were inoculated with 10(6) CFU of S. aureus (Sa) or S. epidermidis (Se) (n = 18 per strain per mesh). The first five meshes are polymer materials while Perm, SIS and Tuto are biomeshes. After 24/48 h of incubation, bacterial adhesion was examined by sonication, scanning electron microscopy (SEM) and light microscopy.

RESULTS

Sa and Se showed a high affinity for the absorbable meshes (TIGR, BioA, Perm, SIS, Tuto) (p < 0.001). Precl yielded the lowest bacterial loads (p < 0.001). Surg, Precl and BioA underwent no substantial change over time, while Op (p < 0.001) and TIGR (p < 0.05) showed decreasing bacterial loads during incubation. The Sa-contaminated biomeshes behaved similarly while biomeshes inoculated with Se returned higher bacterial yields at 48 h, especially SIS (p < 0.001). SEM and light microscopy observations revealed planktonic bacteria and biofilms on the polymer surface and bacterial niches in biomesh pores.

CONCLUSIONS

Within 48 h of contamination, the absorbable polymer and biological meshes exhibited high bacterial loads. Given their lower affinity for both bacterial strains, the conventional non-absorbable polymer materials could be better candidates for use in contaminated surgical fields.

Intraperitoneal behaviour of a new composite mesh (Parietex™ Composite Ventral Patch) designed for umbilical or epigastric hernia repair

INTRODUCTION

The most common treatment option for ventral and umbilical hernias is the implant of a prosthetic mesh. This study compares the behaviour of a new mesh, Parietex™ Composite Ventral Patch (Ptx), with two commercially available meshes, Ventralex™ ST Hernia Patch and Proceed™ Ventral Patch.

MATERIALS AND METHODS

The following meshes were tested in a umbilical-hernia repair model using 54 rabbits: Ventralex™ ST Hernia Patch (Vent) (Bard Davol Inc., USA); Proceed™ Ventral Patch (PVP) (Ethicon, USA) and Ptx (Covidien, Sofradim, France) (n = 18 each). At 3, 7 and 14 days postimplantation, peritoneal behaviour and adhesion formation were assessed by sequential laparoscopy. Adhesions were scored for consistency and quantified by image analysis. The animals were euthanized at 2 (n = 27) and 6 weeks (n = 27) postsurgery. Mesothelial cover of meshes and tissue ingrowth were determined by scanning and light microscopy.

RESULTS

Seroma was observed in 1/18 Vent, 7/18 PVP and 4/18 Ptx, mainly between the implant and subcutaneous tissue. Firm omental adhesions between the mesh and parietal peritoneum were noted in 2/9 Vent, 6/9 PVP and 3/9 Ptx at 2 weeks and in 3/9 Vent, 5/9 PVP and 1/9 Ptx at 6 weeks. Three (out of 9) encapsulated PVP implants showed "tissue-integrated" adhesions affecting the intestinal loops. No differences between implants were detected in the surface area occupied by adhesions at 2 weeks, though at 6 weeks, percentages were significantly higher (p < 0.01; Mann-Whitney U test) for PVP compared to Ptx or Vent. At this time point, Ptx and Vent showed good host tissue incorporation and optimal mesothelialization.

CONCLUSIONS

The PVP implants showed greater adhesion formation than the other materials. Postimplantation behaviour was comparable for Ptx and Vent including scarce adhesion formation and optimal mesothelialization. Regarding tissue integration, Ptx showed greater long-term collagenization of the neoformed tissue.

Extraperitoneal and intraperitoneal behavior of several biological meshes currently used to repair abdominal wall defects

BACKGROUND

This study compares the behavior of several cross- and noncrosslinked biomeshes (Permacol®, CollaMend®, Surgisis®, Tutomesh®, and Strattice®) currently used for abdominal wall repair when implanted intraperitoneally and extraperitoneally. Material and Methods. Intraperitoneal (IP) implants were fixed on the parietal peritoneum and partial abdominal wall defects (EP) were repaired using each of the biomeshes, in the rabbit abdominal wall. After 90 days of implant, the biomeshes were examined to assess biomesh degradation, collagen I and III expression (Sirius red staining) and the host macrophage response (immunohistochemistry). Results. Following implant, the thinner noncrosslinked biomeshes Tutomesh and Surgisis, were almost fully degraded in both models. In contrast, Strattice behavior was similar to crosslinked biomeshes, showing negligible degree of degradation. This mesh also showed high expression of collagen I, similar to the crosslinked. The noncrosslinked materials elicited lower macrophage counts, significantly so for Strattice. In IP and EP models, Permacol showed similarly high macrophages while counts were lower for CollaMend and Surgisis in the EP model. Conclusions. The intra or extraperitoneal implant of the different meshes did not affect host tissue incorporation or mesh degradation. The crosslinked biomeshes induced a more intense macrophage response regardless of their IP or EP location.

Short- and long-term biomechanical and morphological study of new suture types in abdominal wall closure

To perform an abdominal-wall closure, a continuous suture is the preferred method. The suture materials that are most commonly employed in abdominal surgery are polypropylene and polydioxanone. However, in recent times, new products have been marketed, such as non-absorbable polyurethane with elastic properties (Assuplus(®), Assut Europe, Italy) and absorbable barbed polydioxanone (Filbloc(®), Assut Europe, Italy). The purpose of this study was to compare the ability of those against the standard polypropylene (Surgipro(TM), Covidien, USA) and polydioxanone (Assufil(®), Assut Europe, Italy) to mimic the biomechanical behavior of the abdominal wall closure. Comparison of the sutures was made first with the materials alone and later in a laparotomy closure of a rabbit abdomen, used as an animal model. The biomechanical analysis consisted of uniaxial tensile tests of threads and sutured samples of the animal abdomen. In the latter case, results were analyzed at short- (21days) and long- (180days) term intervals after the surgery. The morphology studies and collagen expression of the samples were also investigated. The results determined that polydioxanone and polypropylene sutures showed a linear elastic behavior, with barbed polydioxanone as the most compliant suture and polyurethane as the stiffest. The sutured samples showed a statistically significant loss of resistance, measured as the load needed to perform a certain stretch, when compared with the corresponding control tissue. Analysis of the stress-stretch curves showed that elastic polyurethane was the only suture able to reproduce the mechanical behavior of healthy tissue in the short term, while the rest of the sutures remained less stiff. This coincides with the expression of type I collagen observed in this group at this point in the study. In the long term, there was no difference among the sutures, and none was able to mimic control behavior.

The angiogenesis promoter, proadrenomedullin N-terminal 20 peptide (PAMP), improves healing in both normoxic and ischemic wounds either alone or in combination with autologous stem/progenitor cells

A combination of vascular pathologies and other complicating factors results in chronic wounds which constitute a serious burden for both patients and national health systems, due to prolonged hospital stays, high costs, and prolonged nursing staff dedication. Here we investigate whether proadrenomedullin N-terminal 20 peptide (PAMP), a naturally occurring peptide of the skin with antimicrobial and proangiogenic properties, either alone or in combination with autologous skeletal muscle stem/progenitor cells, acts as a wound healing factor. The rabbit ear was chosen as a test system, since it offers a reliable model for normoxic and ischemic wounds. Topical treatments with PAMP, stem/progenitor cells, or a combination of both, resulted in significant improvements of healing, when compared to untreated wounds. PAMP was very effective in promoting reepithelialization and angiogenesis, whereas treatment with stem/progenitor cells alone resulted in less wound contraction. Interestingly, the combination of PAMP and stem/progenitor cells, while maintaining angiogenic potency, reverted to the contraction levels observed in the untreated controls. Under ischemic conditions, generalized necrosis of the dermis and the underlying cartilage was observed in untreated wounds. Treatments of these wounds with PAMP or stem/progenitor cells allowed a timely recovery. In conclusion, PAMP either alone or in combination with autologous stem/progenitor cells may provide a useful tool for improving wound healing both in normoxic and ischemic conditions.

Long term behavior of biological prostheses used as abdominal wall substitutes

BACKGROUND

Despite their degradation in the host organism, the benefits of collagen bioprostheses remain unclear. This study addresses the absorption and long-term host tissue incorporation of several collagen biomeshes.

MATERIAL AND METHODS

Partial ventral hernial defects created in the abdominal wall of rabbits were repaired using the crosslinked meshes Permacol® or CollaMend®, or the non-crosslinked Surgisis®, Tutomesh® or Strattice®. After 90 and 180 days of implant, morphological studies and morphometric analysis of the thickness of the meshes were performed. Immunofluorescence confocal microscopy combined with differential interference contrast (DIC) imaging was used to distinguish newly formed collagen from that comprising the mesh. The macrophage response was examined by immunohistochemistry.

RESULTS

At 90 days, the thinner non-crosslinked biomeshes Tutomesh and Surgisis were more fully degraded with much of their collagen replaced with loose connective tissue. By 180 days, both implants had been practically fully absorbed. In contrast, in Strattice only the outermost third was infiltrated by neoformed tissue. On both surfaces of the crosslinked meshes, a fibrous capsule with host cells lining its perimeter was observed at both time points, though at 180 days these cells had penetrated the mesh interior. At both implant times, Strattice showed the higher expression of collagen type I while collagen III expression was similar for all the meshes. The non-crosslinked materials elicited lower macrophage counts at both time points, significantly so for Strattice. The macrophage response decreased over time for all the meshes but Surgisis.

CONCLUSIONS

Strattice, the thicker, more compacted non-crosslinked mesh showed the best balance between tissue incorporation and absorption while eliciting a minimal foreign-body reaction in the long-term.

Short-term behavior of different polymer structure lightweight meshes used to repair abdominal wall defects

BACKGROUND

While lightweight (LW) polypropylene (PP) meshes are been used for hernia repair, new prosthetic meshes also of low-density and with large pores have recently been introduced composed of other polymer materials. This study compares the behavior in the short-term of two macroporous LW prosthetic materials, PP and non-expanded PTFE.

METHODS

Partial defects were created in the lateral wall of the abdomen in New Zealand White rabbits and then repaired using a LW PP mesh or a new monofile, LW PTFE mesh. At 14 days postimplant, shrinkage and tissue incorporation, gene and protein expression of neo-collagens (qRT-PCR/immunofluorescence), macrophage response (immunohistochemistry) and biomechanical strength were determined.

RESULTS

Both meshes induced good host tissue ingrowth, yet the macrophage response was significantly greater for the PTFE implants (p⟨0.05). Collagen 1/3 mRNA expression was greater for the PP mesh but differences lacked significance. Similar patterns of collagen I and III protein expression were observed in the neoformed tissue infiltrating the two meshes. After 14 days of implant, tensile strengths were also similar, while elastic modulus values were higher for the PTFE mesh (p⟨0.05).

CONCLUSIONS

In the short term, host collagen deposition and biomechanical performance seemed unaffected by the polymer structure of the implanted mesh. In contrast, the inflammatory response to mesh implant produced at this early time point was more intense for the PTFE.

Immune response to the long-term grafting of cryopreserved small-diameter arterial allografts

INTRODUCTION

The viability and immunological response induced by cryopreserved arterial allografts remain unclear. This study examines the post-graft behaviour of this type of vessel substitute.

MATERIALS AND METHODS

Both iliac arteries were extracted from Lewis rats (donors) and used to establish groups of allogeneic fresh (group I) or cryopreserved (group II) grafts in Fisher-344 rats (recipients). Cryopreserved segments for grafting were prepared by automated controlled freezing at a cooling rate of 1°C/min followed by storage in liquid nitrogen vapour at -145°C for 30 days. Before grafting, the vessels were slowly thawed. Animals were sacrificed at 14, 30, 90 and 180 days post-surgery when graft specimens were obtained for light and electron microscopy and immunohistochemical detection of inflammatory cells (CD45, ED1, CD4, CD8).

RESULTS

After surgery, 85.71% of the grafts in group I and 82.14% in group II were patent. Following long-term implant, both the fresh and cryopreserved allografts showed complete loss of the muscle compartment of the media. Inflammatory or CD45-positive cells (mainly macrophages and CD8 T-lymphocytes) were detected at earlier time points in suture zones and adventitia. In the fresh allografts, the number of immunolabelled cells steadily increased until they were seen to occupy the entire adventitia at 90 days, with high numbers persisting at 6 months. In the cryopreserved allografts, this adventitial inflammatory infiltrate was significantly reduced.

CONCLUSIONS

The cryopreservation/slow thawing protocol used diminished the immune response induced by fresh arterial allografts improving their behaviour after grafting.

Inflammatory reaction and neotissue maturation in the early host tissue incorporation of polypropylene prostheses

PURPOSE

The use prosthetic materials for the surgical repair of abdominal wall defects has become almost standard practice. This study was designed to assess the expression of different growth factors (VEGF/TGF-β1) and macrophages during the early host tissue incorporation of several polypropylene lightweight (PP-LW)-including one partially absorbable-and heavyweight (PP-HW) prosthetic meshes.

METHODS

Ventral defects were created in the anterior abdominal wall of New Zealand rabbits and repaired by fixing PP-LW meshes of different pore size and a low porosity PP-HW mesh to the edges of the defect. Following killing 14 days after implant, specimens were taken to examine TGF-β1/VEGF gene and protein expression by qRT-PCR and immunohistochemistry. The macrophage response was also assessed.

RESULTS

All the materials showed good host tissue incorporation, with a more severe inflammatory reaction and greater numbers of macrophages recorded in the partially absorbable LW implants. Relative amounts of VEGF mRNA were significantly lower for the LW partially absorbable implants compared with the remaining LW meshes. Protein expression of VEGF showed undetectable or minimum staining in the different groups. TGF-β1 mRNA levels were also lower in the partially absorbable group compared with one of PP-LW type of mesh. Gene expression patterns were consistent with the TGF-β1 protein levels detected.

CONCLUSIONS

The results suggest that VEGF and TGF-β1 expression were independent of mesh pore size. The expression of both growth factors and the macrophage response were correlated with the presence of biodegradable material in the mesh. The presence of absorbable material in the LW mesh gave rise to a more intense inflammatory reaction and the reduced synthesis of growth factors known to contribute to neotissue maturation.

[Expression of embryonic markers in pterygium derived mesenchymal cells]

BACKGROUND

Destruction of the limbal epithelium barrier is the most important mechanism of pterygium formation (conjunctiva proliferation, encroaching onto the cornea). It is thought to arise from activated and proliferating limbal epithelial stem cells. The objective of this study is to evaluate the presence of undifferentiated mesenchymal cells (stem cells) in cultured cells extracted from human pterygium.

MATERIAL AND METHODS

Cells from 6 human pterygium were isolated by explantation and placed in cultures with amniomax medium. Once the monolayer was reached the cells were seeded onto 24 well microplates. The cells were studied in the second sub-culture. The immunohistochemical expression of different embryonic stem cell markers, OCT3/4 and CD9, was analysed. The differentiated phenotypes were characterised with the monoclonal antibodies anti-CD31, α-actin and vimentin.

RESULTS

All the cell populations obtained from pterygium showed vimentin expression. Less than 1% of the cells were positive for CD31 and α-actin markers. The majority of the cell population was positive for OCT3/4 and CD9.

CONCLUSIONS

The cell population obtained from pterygium expressed mesenchymal cell phenotype and embryonic markers, such us OCT3/4 and CD9. This undifferentiated population could be involved in the large recurrence rate of this type of tissue after surgery.

Comparison of transient elastography and liver biopsy for the assessment of liver fibrosis in HIV/hepatitis C virus-coinfected patients and correlation with noninvasive serum markers

Transient elastography (FibroScan) is a novel, rapid and noninvasive technique to assess liver fibrosis. Our objective was to compare transient elastography (TE) and other noninvasive serum indexes as alternatives to liver biopsy in HIV/hepatitis C virus (HCV)-coinfected patients. The fibrosis stage (METAVIR Score), TE, the aspartate aminotransferase-to-platelet ratio index, the Forns fibrosis index, FIB-4 and HGM-2 indexes were assessed in 100 patients between January 2007 and January 2008. The diagnostic values were compared by calculating the area under the receiver operating characteristic curves (AUROCs). Using TE, the AUROC (95% CI) of liver stiffness was 0.80 (0.72-0.89) when discriminating between F <or= 1 and F > 2, 0.93 (0.85-1.00) when discriminating between F <or= 2 and F > 3 and 0.99 (0.97-1.00) when discriminating between F <or= 3 and F4. For the diagnosis of F >or= 3, the AUROCs of TE were significantly higher than those obtained with the other four noninvasive indexes. Based on receiver operating characteristic curves, three cutoff values were chosen to identify F <or= 1 (<7 kPa), F >or= 3 (>or=11 kPa) and F4 (>or=14 kPa). Using these best cutoff scores, the negative predictive value and positive predictive value were 81.1% and 70.2% for the diagnosis of F <or= 1, 96.3% and 60% for the diagnosis of F >or= 3 and 100% and 57.1% for the diagnosis of F4. Thus, Transient elastography accurately predicted liver fibrosis and outperformed other simple noninvasive indexes in HIV/HCV-coinfected patients. Our data suggest that TE is a helpful tool for guiding therapeutic decisions in clinical practice.

Inhibition of the intimal hyperplasia in an arterial autograft model by blockade of the N-terminal of the integrin beta3 subunit by monoclonal antibody P37

Myointima formation or intimal hyperplasia is a major undesirable problem at the anastomotic ends of narrow bore arterial autografts and in other arterial wall injuries, which often leads to late restenosis and thrombosis and whose pathogenesis is still not understood. Platelets are suspected to intervene at some stages of its development, together with endothelial and muscle cells, the extracellular matrix and, most probably, adhesion receptors. To ascertain whether and at what stage beta3 integrins are involved, a rat arterial autograft model was used, together with monoclonal antibody P37, which is directed to the sequence 101-109 of the beta3 subunit of the human platelet fibrinogen receptor (integrin alphaIIbbeta3) and inhibits platelet aggregation in vitro and acute thrombosis in vivo. Three groups of animals were used: group I underwent an arterial autograft of a 5-mm segment of the right common iliac artery; group II received, intravenously, a single dose (0.8 mg/kg) of P37 at 15 min before the graft implantation; and group III was treated as group II but a similar dose of antibody was additionally given on day 14 after the operation. Animals in each group were sacrificed on days 7, 14, 21, 30 and 50 after the operation, and the grafts were removed for light and electron microscopy observation and further time-dependent morphometric analysis. By day 14, group I autografts already showed intimal hyperplasia and secretory smooth muscle cells, while group II and II autografts presented only some degenerative changes in the medial layer, with no signs of hyperplasia. Intimal hyperplasia was observed on day 21 in group II and on day 30 in group III, although less pronounced than in the corresponding controls. However, by day 50, the three groups had the same thickness of myointima. The immunohistochemical determination of metalloproteases suggests no role for these enzymes in the immunoinhibition of myointima formation. We conclude that P37 inhibits the onset of the intimal hyperplasia in the arterial autografts and that this onset in treated animals seems to be related to the decay of the circulating antibody. Further work is required to decide whether a higher or longer presence of circulating P37 can definitively prevent the development of intimal hyperplasia, as well as to ascertain which cells and which beta3 integrin receptors intervene.

Comparing the behavior of different polypropylene meshes (heavy and lightweight) in an experimental model of ventral hernia repair

New generation prosthetic biomaterials for abdominal wall repair have been designed to be less dense, by having larger pores than that of the standard polypropylene meshes, to improve abdominal wall compliance. The aim of the present study was to analyze the functional and morphologic properties of these new meshes. For this purpose, 7 x 5 cm(2) defects were created in the anterior abdominal wall of 36 male New Zealand White rabbits and repaired using different polypropylene meshes: a heavyweight mesh (HW), Surgipro, and two lightweight meshes (LW), Parietene and Optilene. Six animals each implanted with biomaterial were sacrificed on postoperative days 14 and 90. Histological and morphometric analysis, adhesion assessment, and biomechanical resistance tests were performed. Similar behavior was shown by the LW and HW meshes in terms of the adhesions and macrophage response induced. After 14 days, the tensile strength of Optilene was greater than the strengths recorded for the other two biomaterials, probably because of its high elasticity. By 90 days, however, the tensile strengths of the three biomaterials were comparable. In conclusion, despite an initial tensile strength advantage shown by the mesh with larger pores, at 90 days postimplant, tensile strengths were similar. Compared with HW, LW prostheses have the benefit that less foreign material was implanted, preserving the elasticity of the recipient host tissue.

Pegylated interferon {alpha}2a plus ribavirin versus pegylated interferon {alpha}2b plus ribavirin for the treatment of chronic hepatitis C in HIV-infected patients

OBJECTIVES

The two currently available types of pegylated interferon (peg-IFN) used to treat hepatitis C have different pharmacokinetic properties. It is unclear how these differences affect response to therapy. We compared the effectiveness and safety of peg-IFN-alpha2a and peg-IFN-alpha2b, both with ribavirin, against chronic hepatitis C virus (HCV) infection in HIV-infected patients.

METHODS

From the GESIDA HIV/HCV cohort, we analysed patients treated with peg-IFN-alpha2a (n = 315) or peg-IFN-alpha2b (n = 242). The primary endpoint was a sustained virological response (SVR).

RESULTS

Both groups were well matched in baseline characteristics except for a higher frequency of injection drug users in the peg-IFN-alpha2b group than in the peg-IFN-alpha2a group (85% versus 76%; P = 0.01) and a higher frequency of bridging fibrosis and cirrhosis (F3-F4) in the peg-IFN-alpha2b group than in the peg-IFN-alpha2a group (42% versus 33%; P = 0.04). End-of-treatment response was significantly lower among patients treated with peg-IFN-alpha2b [40% versus 52%; odds ratio (OR), 1.63; 95% confidence interval (95% CI), 1.16-2.29; P < 0.01]. However, no significant differences were found in SVR between patients treated with peg-IFN-alpha2b and those treated with peg-IFN-alpha2a (31% versus 33%; OR, 1.09; 95% CI, 0.75-1.59; P = 0.655). Therapy was interrupted due to adverse events in 33 (14%) patients treated with peg-IFN-alpha2b and 47 (15%) patients treated with peg-IFN-alpha2a.

CONCLUSIONS

No differences in effectiveness and safety were found between peg-IFN-alpha2b and peg-IFN-alpha2a for the treatment of chronic HCV infection in HIV-infected patients.

Lysyl oxidase like-1 dysregulation and its contribution to direct inguinal hernia

OBJECTIVE

The aetiology of inguinal hernia involves changes in collagen turnover and metalloproteinase expression; yet it is not known whether the elastic fibre system could also be affected. This study was designed to compare the expression of tropoelastin (TE), lysyl oxidase-like 1 (LOXL-1) and elastase in the transversalis fascia of patients with and without inguinal hernia.

MATERIAL AND METHODS

Transversalis fascia (TF) specimens were obtained from patients undergoing surgery for direct or indirect inguinal hernia (n = 20 each) and from multi-organ donors during organ procurement (controls, n = 16). The specimens were divided according to age (20-40/41-60 years). Tissues were immunohistochemically labelled using anti-tropoelastin, anti-LOXL-1 and anti-elastase antibodies and subjected to Western blot analysis. Relative amounts of LOXL-1 and TE mRNA were determined by real time RT-PCR in cultured cells obtained from the TF of patients and controls.

RESULTS

Significantly lower TE and LOXL-1 levels were observed in patients with direct inguinal hernia compared with controls or those with indirect hernia. In contrast, patients with direct inguinal hernia showed significantly higher elastase expression. In fibroblasts isolated from the TF, relative amounts of tropoelastin mRNA were lower for the hernia groups but differences were not significant. LOXL-1 mRNA levels were significantly lower in the direct hernia group compared to controls.

CONCLUSIONS

Our findings suggest that impaired elastic fibre function in the transversalis fascia of patients with direct inguinal hernia, reflected by diminished elastin synthesis and its enhanced enzyme degradation, contributes to the development of this type of hernia.

Monogenic and polygenic models detected in steroid 21-hydroxylase deficiency-related paediatric hyperandrogenism

AIMS

Hyperandrogenism, although mostly due to polygenic interactions, is monogenic for some enzymatic adrenal deficiencies. This study evaluates mono- and biallelic 21-hydroxylase deficiency (21OHD)-related hyperandrogenism in pediatric patients. Sensitizing and protective polymorphisms were investigated in carriers and cryptic forms of 21OHD.

METHODS

The study involved a monogenic analysis of CYP21A2 in patients (375 nonclassical 21OHD [NC21OHD] children; 306 hyperandrogenic 21OHD carriers, n = 306) and a polygenic association study (CAPN10-UCSNP44, PON1-108, TNFR2-M196R, IGF2-ApaI and IRS1-G972R polymorphisms) of 170 hyperandrogenic carriers plus 277 family members (control groups). The metabolic marker 17OH progesterone defined the degree of deficiency; clinical expressivity was determined by pediatric endocrinologists.

RESULTS

The group of 21OHD carriers manifesting hyperandrogenism was enriched in the CAPN-UCSNP44 rare variant in homozygosity (4.9 vs. 0.4%, NCBI data for the general population; p = 0.004). In our patients and controls, contrasting distributions were observed for this and another polymorphism, TNFR2-196R. In a recessive model, their rare variants were more frequently detected among the forms with high (p = 0.048) and low (p = 0.034) expressivity respectively.

CONCLUSIONS

21OHD-related pediatric hyperandrogenism follows monogenic and polygenic models. The opposite behaviors in terms of clinical expressivity detected for CAPN-UCSNP44 and TNFR2-M196R rare variants suggest these variants to be sensitizing and protective factors respectively in adrenal hyperandrogenism.

Down-regulation of lysyl oxydase-like in aging and venous insufficiency

BACKGROUND

Elastin expression is higher in tissues where elastic fibres are essential for the correct maintenance of function such as blood vessels. Elastin expression usually diminishes with age, however, it may be re-expressed in response to injury or repair processes. Some authors attribute the characteristic loss of elasticity of the varicose vein to a drop in the population of smooth muscle cells in the media layer. A reduction in elastin has been observed in chronic venous insufficiency, but little is known about some of the factors involved in elastin synthesis such as lysyl oxidases. The aim of this study was to examine the in vivo expression of the elastin precursor, tropoelastin (TE), and lysyl oxidase-like 1 (LOXL1), a cross-linking enzyme responsible for elastin polymer deposition. The effects of age on these expression patterns were also evaluated.

METHODS

Saphenous vein segments were obtained during surgery from organ donors (controls, n=20) and subjects with venous insufficiency (varicose veins, n=20). Both these groups were subdivided according to subject age into <50 years (n=10) and >or=50 years (n=10). Control and varicose vein tissue specimens were immunolabelled using anti-tropoelastin and anti-LOXL1 antibodies and also subjected to Western blot analysis.

RESULTS

Our results indicate that the levels of these markers of elastin synthesis (LOXL/tropoelastin) in the vein wall diminish in a significant way (p<0.05) with the age factor. Excluding the age factor, LOXL1 was significantly decreased in the varicose condition (p<0.05). In the younger pathological population they showed an inverse relationship (LOXL decreased, tropoelastin increased).

CONCLUSIONS

The already established reduction in elastin in the varicose condition may be related, at least in part, to the decreased LOXL1 levels observed here. These events could reduce spontaneous reticulation of elastin and the partial loss of tissue elasticity in this group of patients.

Identification of liver fibrosis in HIV/HCV-coinfected patients using a simple predictive model based on routine laboratory data

We constructed noninvasive models to predict significant fibrosis (F > or = 2) and advanced fibrosis (F > or = 3) among human immunodeficiency virus (HIV)/hepatitis C virus (HCV)-coinfected patients, naïve for anti-HCV treatment. A total of 296 patients with liver biopsy were randomly assigned to an estimation group (EG = 226; 70%) and a validation group (VG = 70; 30%). We developed the Hospital Gregorio Marañón (HGM)-1 index, based on platelet count, aspartate aminotransferase (AST) and glucose, to predict F > or = 2 and the HGM-2 index, based on platelet count, international normalized ratio, alkaline phosphatase and AST to predict F > or = 3. The area under the receiver operating characteristic curves (AUROCs) of the HGM-1 index for the EG and the VG were 0.807 and 0.712 respectively. The AUROCs of the HGM-2 index for the EG and the VG were 0.844 and 0.815 respectively. With the HGM-1 index applied to the VG, using best cutoff scores, the negative predictive value (NPV) to exclude F > or = 2 was 54.5% and the positive predictive value (PPV) to confirm F > or = 2 was 93.3%. With the HGM-2 index applied to the VG, using best cutoff scores, the NPV to exclude F > or = 3 was 92.3, and the PPV to confirm F > or = 3 was 64.3%. Thus, HGM-2 accurately predicted F > or = 3 among HIV/HCV-coinfected patients. HGM-1 was less accurate at predicting F > or = 2.

TGF-beta1 overexpression in the transversalis fascia of patients with direct inguinal hernia

BACKGROUND

The aetiology of inguinal hernia includes changes in collagen turnover and metalloproteinase (MMP) expression, and direct hernia has been linked to increased MMP-2 expression. Since transforming growth factor beta1 (TGFbeta1) plays a role in tissue remodelling, this growth factor could directly affect metalloproteinase secretion and thus the proteolytic activity of these enzymes. We hypothesized that TGFbeta1 expression could also be altered in direct inguinal hernias.

MATERIALS AND METHODS

Tissue specimens were obtained from the transversalis fascia (TF) of organ donors (controls; n = 10) and patients with inguinal hernia (indirect; n = 20/direct; n = 20), who were also divided into two groups according to age (20-40/41-60 years). Tissue sections were immunohistochemically labelled using anti-LAP TGFbeta1 (latent form) and anti-TGFbeta1 (active form) antibodies, and fragments of tissue were subjected to Western blot analysis.

RESULTS

No significant differences in LAP-TGFbeta1 expression were detected between specimens from control and hernia patients. However, significantly higher levels of active TGFbeta1 were detected in the TF of patients with direct hernia (P < 0.05). Age affected the expression of the growth factor in its active form, and significant differences emerged between direct hernias and controls/indirect hernias only in the younger age groups.

CONCLUSIONS

Our findings indicate overexpression of the active form of TGFbeta1 in the TF of young patients with direct hernia. This overexpression reflects an attempt to counterbalance the enhanced matrix degradation process observed in these patients, identifying a subset of patients requiring the use of a prosthetic material for primary hernia repair.

Efficiency of 4% Icodextrin in Preventing Adhesions to Spiral Tacks Used to Fix Intraperitoneal Prostheses

BACKGROUND/AIMS

This study was designed to evaluate the extent of adhesion formation to prostheses fixed with spiral tacks and to establish whether the use of Ringer's lactate or icodextrin could prevent these adhesions.

METHODS

24 New Zealand white rabbits weighing around 3,000 g were implanted with a 7 x 5 cm patch of ePTFE (DualMesh) through a midline laparotomy. The prosthesis was fixed to the intact peritoneum using spiral tacks. Three study groups were established according to whether the animals were: implanted with ePTFE fixed with spiral tacks or implanted with ePTFE fixed with spiral tacks and simultaneously administered Ringer's lactate or 4% icodextrin in the peritoneal cavity. Adhesion formation and prosthetic behavior at the prosthesis/peritoneal interface were evaluated and quantified by sequential laparoscopy performed at 3, 7 and 14 days.

RESULTS

Adhesions generally formed on the tacks and were classified as the fully integrated type. No significant differences were observed in terms of the extent of adhesions or of neoperitoneal thickness between control animals and those receiving Ringer's lactate or icodextrin.

CONCLUSIONS

(a) Prosthesis-fixing tacks induced adhesions; (b) the use of substances such as icodextrin or Ringer's lactate does not seem to diminish adhesion formation, and (c) the use of icodextrin offered no benefits over that of Ringer's lactate solution.

Influence of the structure of new generation prostheses on shrinkage after implant in the abdominal wall

When a biomaterial is used to repair an abdominal wall defect, wound contraction can cause the prosthesis to shrink, and the tension generated can provoke recurrence of the defect. This study was designed to determine whether the structure of a prosthesis can directly influence prosthetic shrinkage. Abdominal wall defects (7 x 5 cm) in rabbits were repaired using the laminar prosthesis DualMesh (DM), the composites Sepramesh (Se) and Vypro II (Vy), and the reticular prosthesis Surgipro (PP). The animals were sacrificed 14 and 90 days after surgery, at which time implant specimens were morphologically and immunohistochemically examined to establish the presence of myofibroblasts and macrophages. The size of each prosthesis was measured at the end of the study through image analysis. Morphometric measurements revealed greatest prosthesis shrinkage for Se, PP, and Vy (16.05% +/- 5.08%; 13.75% +/- 4.22%; 16.16% +/- 6.34%), while the DM prostheses only showed a 7.57% +/- 0.62% decrease in size (p < 0.05). In the DM implants, the macrophage response and myofibroblast labeling were reduced. Both biomaterial structure and the macrophage reaction induced at the implant site modulate prosthetic shrinkage, laminar prostheses of the ePTFE type undergoing less shrinkage than reticular meshes. Reduced DM shrinkage was linked to decreased myofibroblast numbers 2 weeks postimplant.

[Dengue infection in children and adolescents in Panama]

BACKGROUND

Dengue is a serious emerging infectious disease and constitutes a major international health concern.

MATERIAL AND METHODS

All reports of confirmed dengue infection in patients aged less than 18 years old between 2000 and 2005 were included. A confirmed diagnosis was established by culture of the virus within the first 3 days of symptom onset or by serologic assays 5-30 days after symptom onset. Clinical and epidemiological features were analyzed.

RESULTS

A total of 457 patients were included (57.6 % female). The median age was 13 years (IQR 5 6). A greater number of cases were detected in urban areas and during the rainy season (May-November). Two epidemics were reported in 2001 (33.9 %) and the first eight months of 2005 (23.1 %). The most prevalent symptoms were fever (95.2 %), severe headache (74.2 %), chills (65.9 %), rash (63.5 %), myalgias (51.9 %) and retro-orbital pain (51.6 %). No significant differences were found between male and female patients. Significant differences in clinical features were found when the patients were divided into 3 groups; < 5 years old, 6-10 years old and > 10 years old. Fifty-three percent of the patients had had previous contact with a dengue-infected individual. There were 7 patients with dengue hemorrhagic fever, 4 of whom died.

CONCLUSIONS

Dengue virus infection is still a major health problem in Panama. To achieve effective control of dengue, further epidemiological studies, such as our own, are needed to design appropriate preventive measures.

Muscle-derived stem cells in tissue engineering: defining cell properties suitable for construct design

The terms construct or tissue equivalent refer to neotissue produced by tissue engineering techniques. The elements forming the construct are scaffolds on which cells are "recreated" to form an engineered-tissue sensitive to certain cell signals. The ability of the cells to expand and differentiate on the scaffold is determined by properties such as fixation, adhesion, proliferation and migration. Among the cell types that seem to be most promising for designing constructs are tissue-residing, or adult, stem cells, which show two main features: a capacity to differentiate into many cell lineages and the power of self-renewal. These features make them good candidates for cell replacement therapies. Here, we report the identification, isolation and culture of muscle stem cells aimed at establishing the ideal culture in terms of defining when the cultured cell population would show optimal characteristics for transfer to the scaffold to obtain a particular construct. Stem cells harvested from the dorsal muscle of white New Zealand rabbits were cultured in vitro and characterized 5 to 14 days after the start of culture. Fibroblasts obtained from the same experimental animal served as controls. The stem cells were examined by light and scanning electron microscopy. For stem cell identification, we used the antibodies anti-m-cadherin, anti-CD34 and anti-Myf-5. The markers of muscle differentiation used were: anti-vimentin, anti-alpha-actin, anti-desmin and anti-myosin. The expression profiles of the different markers of muscle differentiation and TGFbeta1 in the cell cultures were confirmed by Western blotting. Proliferation rates were determined by monitoring tritiated thymidine incorporation. The thymidine incorporation rate was substantially higher for the population of undifferentiated cells than for control fibroblasts obtained from the same animal. During the first five days of culture, most cells were negative for all the markers examined, with the exception of m-cadherin, CD34 and Myf-5, although discrete signs of vimentin expression started to emerge. After 14 days of culture, the adult stem cells showed vimentin (94.2%) and desmin (33.8%) expression yet scarce labeling for myosin (16.2%) and alpha-actin (8.3%). Control fibroblasts showed intense labeling for vimentin (99.3%) and alpha-actin (62.2%), while less than 2% of the population expressed myosin (0.9%) and desmin (1.6%). After two weeks of culture, muscle-derived stem cells show good proliferative and adhesion properties as they initiate differentiation. These conditions seem ideal for obtaining the desired construct.

Composite prostheses for the repair of abdominal wall defects: effect of the structure of the adhesion barrier component

The component of a composite prosthesis, which makes contact with the visceral peritoneum, can be reabsorbable or non-reabsorbable, and laminar or reticular. This study was designed to determine whether the composition of this second, barrier component could improve its behavior at this interface. Abdominal wall defects in rabbits were repaired using a polypropylene prosthesis (PP), or the composites Sepramesh (PP + h) or Vicryl (PP + v). Fourteen days after surgery, the implants were evaluated by light and scanning electron microscopy, and immunohistochemistry. Prosthetic areas occupied by adhesions (PP: 71.08 +/- 5.09, PP + h: 18.55 +/- 4.96, P + v: 69.69 +/- 16.81%), neoperitoneal thickness (PP: 256.17 +/- 21.68, PP + h: 83.11 +/- 19.63, PP + v:213.72 +/- 35.90 microm) and macrophage counts (PP: 8.73 +/- 1.16, PP + h: 27.33 +/- 4.13, PP + v: 31.24 +/- 3.08%) showed significant differences (P < 0.05). The tested biomaterials induced an optimal recipient tissue infiltration. Least adhesion formation was observed on the PP + h implants. This suggests that the second component, although reabsorbable, should be smooth in structure.

Patency and structural changes in cryopreserved arterial grafts used as vessel substitutes in the rat

OBJECTIVE

To evaluate the patency and structural changes that occur in the short- and mid-term when cryopreserved syngenic arterial grafts are implanted in an experimental animal model.

MATERIAL AND METHODS

Segments of iliac artery from the Spraque-Dawley rat were cryopreserved in a biological freezer according a controlled, computerized freezing protocol whereby the specimens are cooled at a rate of 1 degrees C/min. After storage at -145 degrees C in liquid N2 vapor for 30 days, the cryografts were slowly thawed. These vessels were grafted to the common iliac artery in syngenic animals. The following study groups were established: group I (GI), non-implanted cryografts; group II (GII), autografts; and group III (GIII), cryoisografts. The control group (CG) was comprised of fresh iliac arteries. The animals were sacrificed 14, 30, or 90 days post-surgery. At each of these follow-up times, graft specimens were morphologically evaluated by light and scanning and transmission electron microscopy and immunolabeling of endothelial cells (vWf). Cell damage attributed to the cryopreservation or grafting process was also determined.

RESULTS

At the time of sacrifice, graft patency was 100% for the autografts, while 26.6% of the cryoisografts showed fully occlusive thrombosis. Among other complications, two pseudoaneurysms were detected. After cryopreservation, the grafts (GI) showed patches of endothelial denudation and good cellularity of the medial layer. The intimal hyperplasia observed in autografts implanted for 14 days (GII) was significantly delayed until day 30 when the graft was cryopreserved (GIII). Cryoisografts showed general thinning of the arterial wall and degeneration accompanied by medial layer cell loss. These grafts showed most cell damage at 90 days post-implant. Expression of the vWf in all specimens showing intimal hyperplasia was confined to the outermost graft layer.

CONCLUSIONS

Cryopreservation modified the reparative response of the grafts. Owing to faster degeneration of the medial layer and a delay in the appearance of intimal hyperplasia, arterial wall thickness was reduced relative to that of the non-cryopreserved autografts. This thinning, at least in the short-term (90 days), does not seem to give rise to aneurysms owing to the generation of a neointima that stabilizes the vessel wall.

Histological evaluation of scar tissue inflammatory response: the role of hGH in diabetic rats

This paper describes a polymer site-specific delivery system containing human growth hormone in an in vivo model of scarring in the diabetic state. Copolymer discs with the hormone were introduced into incisions made in rats previously injected with streptozotocin in order to induce diabetes. Tissue specimens for evaluation were obtained at 3, 7 or 10 days after the procedure. Study groups were healthy rats and diabetic rats untreated or treated with/without the hormone. Histological sections were prepared for light microscopy examination of wound zones. Three and 7 days after surgery, polymer remains could be observed in the subcutaneous tissue. These remnants induced a moderate foreign body reaction. The number of macrophages detected was directly related to neovessel formation and metalloelastase expression. The CD4+/CD8+ ratio was low during the initial follow up stages (3 and 7 days) in untreated diabetic rats, yet an increased ratio corresponding to areas around the polymer remains was noted in the animals treated with copolymer loaded with the growth hormone. Copolymer is biodegradable in vivo and may be used as a vehicle for the slow release of active substances. The presence of the hormone at the site of skin injury induces cell proliferation and enhances the repair process.

Homeostatic role of IL-7 in HIV-1 infected children on HAART: association with immunological and virological parameters

AIM

To investigate the role of IL-7 in HIV-infected children on highly active antiretroviral therapy (HAART) and its association with laboratory parameters related to disease progression.

PATIENTS AND METHODS

A cross-sectional study in 31 vertically HIV-infected children (median age 8.4 y) treated with HAART, and a longitudinal study in four of those same children was carried out. In both studies, viral load, CD4+ T-cell counts, thymic production of T cells by TCR rearrangement excision circles (TRECs), IL-7 plasma levels and viral phenotype were determined.

RESULTS

IL-7 levels were higher in HIV-infected children than in age-matched, uninfected controls. In addition, HIV children with CD4+ T cells between 200 and 500 T cells/mm3 had higher IL-7 levels and lower TREC values than HIV-infected children with CD4+ T cells >500 T cells/mm3. IL-7 levels were higher in children with syncytium-inducing (SI) phenotype than in those with non-syncytium-inducing (NSI) variants. During the follow-up of four HIV children, the decrease in viral load after HAART was always associated with a recovery of CD4+ T cells and TRECs, which was followed by a decrease in IL-7 returning to the levels present prior to the drop in CD4+ T cells. The four HIV-infected children had SI/X4 isolates in PBMC before HAART, and the viral phenotype switched to NSI/R5 after HAART.

CONCLUSION

Our data suggest that IL-7 plays a key role in the maintenance of T-cell homeostasis in HIV-infected children on HAART, both through peripheral expansion and through a thymus-dependent mechanism.

Composite prostheses used to repair abdominal wall defects: Physical or chemical adhesion barriers?

In a composite prosthesis, the component placed at the peritoneal interface takes the form of a physical or chemical barrier. In this experimental study performed on the white New Zealand rabbit, several composites were examined to establish the effectiveness of these barriers at impeding adhesion formation. The biomaterials tested were two polypropylene prostheses (PP) with the physical barriers of expanded polytetrafluoroethylene or polyurethane (PP + ePTFE and PP + PU) and two prostheses (one polyester and the other PP) with the absorbable chemical barriers of polyethylene glycol/glycerol and hyaluronate, respectively (PO + gl and PP + hy). The composites were used to repair 7 x 5 cm defects created in the abdominal wall of the animals by placing the implant in contact with the visceral peritoneum and the subcutaneous tissue and fixing it to recipient tissue by 4/0 polypropylene running suture. Fourteen days after surgery the animals were sacrificed and specimens were taken for light microscopy and scanning electron microscopy. Adhesions developing at the prosthesis/visceral peritoneal interface were quantified. All the prostheses induced optimal mesothelialization. Composites with physical barriers behaved similarly in terms of provoking adhesions. However, the prostheses with chemical barriers differed in their effectiveness at preventing adhesions. Overall, the best results were obtained with the PP + PU composite.

Tissue integration and biomechanical behaviour of contaminated experimental polypropylene and expanded polytetrafluoroethylene implants

BACKGROUND

Infection is one of the most devastating complications following implantation of a prosthetic material. The aim of this study was to compare the behaviour of two biomaterials contaminated with Staphylococcus aureus or Staphylococcus epidermidis, used to repair abdominal wall defects.

METHODS

Defects (7 x 5 cm) were created in the anterior abdominal wall of 60 white New Zealand rabbits and repaired using polypropylene or expanded polytetrafluoroethylene (ePTFE) prostheses. The site of repair had been previously inoculated with 10(6) colony-forming units/ml S. aureus or S. epidermidis. Seven and 30 days after implantation, prosthetic specimens were examined by light and scanning electron microscopy, and immunohistochemical and biomechanical analysis.

RESULTS

No significant differences with respect to controls were observed in the S. epidermidis groups. Two animals inoculated with S. aureus died. S. aureus induced the appearance of denuded areas exposing the filaments in the polypropylene prostheses, whereas the ePTFE prostheses showed zones of erosion, disorganized tissue, haemorrhage and necrosis. The biomechanical strength of the contaminated implants was unaltered.

CONCLUSION

Integration within host tissue was affected in the setting of S. aureus infection but the tensile strength of contaminated prostheses was not significantly reduced.

Long-term Behaviour of Cryopreserved Arterial Grafts Versus Prosthetic Micrografts

INTRODUCTION

When a patient has no suitable vessels for use as grafts in bypass or reconstruction procedures, two of the options available are the use of a cryopreserved vessel or an expanded polytetrafluoroethylene (ePTFE) prosthesis. This study was designed to compare the long-term behaviour of these vascular substitutes.

MATERIAL AND METHODS

We established three study groups by grafting the following vessel substitutes to the iliac artery in Spraque-Dawley rats: arterial autografts (GI, n=12), cryopreserved syngenic arterial grafts (cryoisografts) (GII, n=12), and ePTFE micrografts (GIII, n=12). The animals were sacrificed 180 days after surgery, at which time the graft specimens were morphologically evaluated by light and electron microscopy, immunolabelling (ED1/alpha-actin) and morphometric analysis of the neointima.

RESULTS

At the time of sacrifice, graft patency was 100% for the autografts and cryoisografts, while 10% of the ePTFE micrografts showed fully-occlusive thrombosis. Intimal hyperplasia was observed in grafts in GI and GII; the neointima being thinner in the cryoisografts (54.36 +/- 2.26 microm) than the autografts (161.30 +/- 3.91 microm). The endothelium formed over the prosthetic micrografts was unstable, with areas of subendothelial thickening (9.37 +/- 3.18 microm). Cell loss and medial layer degeneration were observed in both GI and GII specimens, while the GIII grafts were colonised by cells on their luminal surface.

CONCLUSIONS

All three grafts show good long-term tolerance when used in an arterial setting. Following long-term implant, autografts and cryoisografts show similar alterations that give rise to the complete loss of the muscle component of the tunica media along with the formation of a stable neointima. This new layer takes on the role of the tunica media.

Modulatory role of IL10 in endothelial cell damage and platelet adhesion

This study explores the possibility of a regulatory role for cytokine IL-10 in platelet aggregation as an active vascular repair mechanism. Endothelial cells from human umbilical cord vein were cultured in the presence of different IL-10 concentrations (0-100 ng/ml). Platelet-rich plasma was then added to these cultures and allowed to act for 30 minutes. To rule out blood plasma involvement, washed platelets were also incubated with IL-10 (0-100 ng/ml). Changes in endothelial cell morphology were observed depending on the IL-10 concentration used; apoptotic cells appearing at the highest IL-10 concentration. Greatest platelet adhesion was noted at the highest IL-10 concentration. It was concluded that, in this in vitro model, low IL-10 levels do not affect cell viability or the pattern of platelet adhesion, but at high doses, this cytokine induces cell death and enhances platelet deposition.

Inflammatory cells induce neointimal growth in a rat arterial autograft model

Subendothelial invasion by leukocytes is a sign of intimal thickening in arteriosclerosis and in the response of a vessel to mechanical damage. Our study was designed to establish whether these cells are implicated in the formation of a neointima in an autologous arterial graft model in the rat and to evaluate the effects of cyclosporin A (CsA). Three study groups were established according to whether the animals were treated with CsA-Cp (Sandimmun), CsA-Et (ethanol vehicle) or received no treatment (control group). Both drug forms were administered (5 mg/kg/day, s.c.) from 4 days prior to surgery until the time of sacrifice. Antibodies specific for lymphocytes (CD4, CD8), monocytes/macrophages-ED1, smooth muscle alpha-actin and the von Willebrand factor (vWF) were used to identify the cells in the grafted arterial wall. In control grafts, the neointima had formed by 2 weeks post-implant. However, the cells comprising this layer generally presented no positivity whatsoever towards the antibodies employed. At 50 days, the new layer was observed to be formed by a vWF-positive endothelium and alpha-actin-positive cells. In all three groups, several polymorphonuclear (PMN) cells adhered to the denuded luminal surface from 7 days onwards. In the treated animals, neutrophils and monocytes were seen to infiltrate intimal and medial layers during the later post-implant stages. Around the third week post-implant, the neointima had reached the grafted segment from the distal portion of the recipient artery, and by 50 days it was similar to that seen in control specimens. Our findings suggest that: a) neutrophils play a role in neointimal thickening in this arterial autograft model; and b) CsA promotes the adhesion and infiltration of neutrophils in the injured arterial wall.

In vitro mesothelialization of prosthetic materials designed for the repair of abdominal wall defects

The aim of this study was to evaluate the in vitro response of mesothelial cells (MC) in terms of their ability to cover different biomaterials. MC were harvested from human omentum. The MC from the first passage were seeded onto different biomaterials from 10 min to 24 h: PL-PU99 (polypropylene-polyurethane); DM (ePTFE); PL (polypropylene); and PL + Col (polypropylene-collagen). The prosthetic surface covered was examined by microscopy and quantified. PL-PU99: The MC were adhered to the biomaterial 10 min post-incubation. At 4 h, the 53.12+/-7.86% of the prosthesis were coated with polygonal cells. At 12 h, 96.32+/-11.32% of the biomaterial was coated. DM: between 30 min to 8 h, the MC cells form small, round colonies. At 12 h, polygonal and fusiform secretory cells were observed (68.94+/-5.78%). 93.54+/-11.49% of surface was coated after 24 h. PL: only isolated cells were observed on the prosthesis. PL + Col: MC form a monolayer over prosthetic surface after 18 h (90.21+/-9.76). We conclude: (a) MC formed a stable monolayer over all the biomaterials tested with the exception of the PL due to its porosity. (b) The PL-PU99 showed the greatest potential for in vitro mesothelialization compared to the PL-Col and DM prostheses.

Preserved immune system in long-term asymptomatic vertically HIV-1 infected children

The objective of this study was to study immune system status in long-term asymptomatic (LTA) HIV-1-infected children. A cross-sectional study was used, involving HIV-1-infected children over 7 years of age who were rated into two groups according to their clinical and immunological classification: (a) LTA: 7 asymptomatic HIV-1-infected children in A1; (b) Rapid progressor (RP): 14 age-matched C3 HIV-1-infected children. The control group consisted of 17 age-matched uninfected children. The characterization of CD4+ T-cell subsets was determined by three-colour flow cytometry. The proliferative response and cytokine production by activated peripheral blood T-cells were also measured. IL-7 levels were measured in serum. Thymic production of T-cells was quantified by TCR rearrangement excision circles (TRECs). The LTA children showed similar proliferative responses to PHA, PWM and anti-CD3+ anti-CD28, but lower responses to tetanus toxoid and streptokinase, in comparison with the controls but always higher responses in comparison with the RP group. The production of TNF-alpha and IFN-gamma was similar in the LTA and control groups, and both were higher than the levels in the RP group. The LTA group showed a lower percentage of memory CD4+ T-cells (CD4+ CD45RO+, CD4+ CD45RA-CD62L+) than the control and RP groups. The LTA group also showed lower percentages of CD4+ CD7- cells than the controls. As for naïve CD4+ T-cells (CD4+ CD45RA+ CD62L+), CD4+ CD45RA+ and CD4+ CD62L+ cells, the LTA group showed higher values than the control and RP groups. The LTA group showed higher percentages of CD4+ HLA-DR+ CD38+ than the controls, but lower values than the RP group. In contrast, the LTA group had percentages of CD4+ HLA-DR-CD38+ T-cells higher than both the control and RP groups, whereas CD4+ CD38+ levels were only higher in the LTA group in comparison with the controls. CD4+ HLA-DR+ CD38- and CD4+ HLA-DR+ cell numbers were lower in the LTA group in comparison with the RP group. We found almost normal values of TRECs and IL-7 in the LTA group, but lower values in the RP group. Moreover, we found an inverse relation between TREC levels and IL-7 in plasma from HIV-infected children. Asymptomatic HIV-1 infected children have a well preserved immune system similar to that of control uninfected children in spite of HIV-infection for more than 7 years. Moreover, our results identified new markers of HIV disease, such as TRECs and IL-7, that could be used to monitor disease.

Dynamics of progression markers in a non-study population of human immunodeficiency virus-1 vertically infected infants with different antiretroviral treatments

Treatment with highly active antiretroviral therapy (HAART) has been shown to modify viral replication dynamics and lead to a significant recovery of CD4+ T-cells. A retrospective multicentre observational study was performed in a non-study population of 151 HIV-1-infected children, categorized into four groups according to therapy: untreated (NT), on monotherapy (MT) with a nucleoside inhibitor, on combination therapy (CT) with two nucleoside inhibitors, and on HAART, protease inhibitor containing regimens, to assess the "real-life" effectiveness of these different therapies on plasma viral load (VL) and CD4+ T-cells. VL was quantified using a standard molecular assay. CD4+ and CD8+ T-cells subsets were determined by flow cytometry. The HAART group showed the highest relative proportion (RP) of increases in 5, 10, 15 and 20% of CD4+ T-cells over baseline, and the earliest fall-off of VL (0.5, 1, 1.5 and 2 log10 copies ml-1). The RP of the fall-off of 0.5, 1, 1.5 and 2 log10 VL below baseline was 3-fold higher in HAART group than in the MT and CT groups. However, no differences were found among the groups of treated children in reaching undetectable VL.

CONCLUSION

A better evolution of VL and CD4+ T-cells was evident in children on HAART, indicating a positive effect on the immune system and clinical status, inhibiting HIV-1 replication and enabling the recovery of CD4+ T-cell counts.

Stimulated proliferative responses in vertically HIV-infected children on HAART correlate with clinical and immunological markers

The objective of the study was to investigate the relationship between various CD4+ T cell subsets and the ability of peripheral blood mononuclear cells (PBMC) to proliferate to several stimuli in vertically human immunodeficiency virus type 1 (HIV-1)-infected children. We studied 29 HIV-1-infected children on highly active antiretroviral therapy (HAART) (median duration: 12.3 months). T cell subsets were determined by flow cytometry. Plasma viral load (VL) was quantified using a standardized molecular method. Proliferative responses were evaluated by [3H]-thymidine incorporation. Decreased proliferative responses of PBMC to pokeweed mitogen (PWM) were found for HIV-1-infected children in Centers for Disease Control (CDC) clinical categories B and C when compared to the control group (P < 0.05). Similarly, children with < or = 15% CD4+ T cells showed a decrease in proliferative responses to PWM (P < 0.01), anti-CD3 + anti-CD28 (P < 0.01) and phytohaemagglutinin (PHA) (P < 0.05) with respect to the control group and to children with CD4+ T cells > or = 25%. Proliferative responses to PWM, anti-CD3+, anti-CD28 and PHA had a statistically significant positive correlation with CD3+/mm3, CD4+/mm3, % CD4 T cells, CD4/CD8 ratio and the percentage of naive T cell subsets (CD4+CD45RO-HLA-DR-, CD4+ CD45RA+ CD62L+, CD4+ CD45RA+), CD4+ CD62L+ and CD4+ T cells co-expressing CD38+ (CD4+ HLA-DR-CD38+, CD4+ CD38+). Moreover, we found a negative correlation between PBMC proliferative responses and % CD8 T cells, memory, memory-activated and activated CD4+ T cell subsets. Lower proliferative responses to PWM (P < 0.01) and PHA (P < 0.01) were associated with higher VL. Our data show that higher proliferative responses to PWM, anti-CD3 + anti-CD28 and PHA are associated with both non-activated and naive CD4+ T cell subsets in HIV-1-infected children on HAART.

A novel controlled drug-delivery system for growth hormone applied to healing skin wounds in diabetic rats

Controlled release systems for drugs, hormones and growth factors can be particularly useful in tissue repair processes. These systems act as a biodegradable support containing the substance to be delivered, allowing their gradual release. In the past years, the local application of growth factors has acquired special relevance as a therapeutic option for use in subjects who show deficient tissue scarring, the hormone dose being the limiting factor for its success. In this study, the in vitro biocompatibility of a copolymer formed by vinylpyrrolidone and 2-hydroxyethyl methacrylate, used as an administration vehicle for hGH, was evaluated. The system was then tested in vivo in terms of its capacity for healing incisional wounds in healthy and diabetic rats. For the in vitro studies, polymer and hormone degradation rates were determined, and polymer biocompatibility was evaluated in fibroblast cultures. In the in vivo experiments, an incision was made in the back of the animals, and polymers discs with/without hGH, were introduced in the aperture. Morphological, immunohistochemical and morphometric evaluations were performed on wound tissue specimens 3-10 days after surgery. In vitro, the polymer was found to be biodegradable and showed no toxic effects on fibroblasts, the hormone being slowly released to the culture medium. In untreated diabetic rats, a delayed skin scarring and cell response were observed, compared to that noted in healthy animals. Skin closure, keratinisation and fibrosis occurred earlier in the presence of the polymer-hGH system. The use of this co-polymer as an administration vehicle for hGH improves the wound scarring process in the pathological setting of diabetes.