Arterial elasticity measurement in renal transplant recipients

Arterial distensibility is reduced in chronic kidney disease (CKD) and after kidney transplantation. Pulse counter analysis provides an assessment of compliance or elasticity of the large conduit arteries (C1) and small arteries (C2). Decreased compliance has been shown to be predictive of primary coronary events in CKD patients. The aim of the present study was to compare elasticity measurements in hemodialysis (HD) patients, renal transplant recipients (RTR), and healthy subjects whose coronary angiographies were without lesion. Twenty-three RTRs, 18 HD patients, and 20 healthy subjects were included in the study. Pulse wave analysis was used to determine large and small vessel compliances. The C1 and C2 levels were significantly lower in HD patients compared with recipients and healthy subjects. Recipients showed lower C2 level compared with healthy subjects. There was no difference in C1 and C2 measurements between recipients receiving tacrolimus versus cyclosporine. Transplantation improves large and to some extend small artery elasticities in CKD patients.     

End-to-end microvascular anastomosis in the rat carotid artery using continuous horizontal mattress sutures

This paper reports a continuous horizontal mattress suture technique with advantages such as decreased time for anastomosis, minimized anastomotic leakage, eversion around the vessel edges, and other advantages which the continuous anastomosis technique has. This technique was compared with the classical interrupted and classical continuous suture techniques on a total of 59 Sprague-Dawley rat common carotid arteries: Group 1 (n = 19), interrupted suture technique; Group 2 (n = 20), standard continuous technique, and Group 3 (n = 20), continuous horizontal mattress technique. Early (30 min) and late (21 days) patency rates, anastomosis time, leakage on clamp release, oozing duration, additional sutures needed, and total number of sutures placed were statistically compared between groups. Specimens were taken at the 21st day randomly, and light microscopy (LM), scanning electron microscopy (SEM), and angiographic studies were performed. Results revealed that the continuous mattress suture technique has the advantages of providing a water-tight anastomosis with less suture materials in a shorter time, and minimal intraluminal suture material which can incite thrombosis. On the other hand, a tendency to anastomotic stricture was found to be the sole disadvantage of this technique.     

Self-assembly of the general membrane-remodeling protein PVAP into sevenfold virus-associated pyramids

Viruses have developed a wide range of strategies to escape from the host cells in which they replicate. For egress some archaeal viruses use a pyramidal structure with sevenfold rotational symmetry. Virus-associated pyramids (VAPs) assemble in the host cell membrane from the virus-encoded protein PVAP and open at the end of the infection cycle. We characterize this unusual supramolecular assembly using a combination of genetic, biochemical, and electron microscopic techniques. By whole-cell electron cryotomography, we monitored morphological changes in virus-infected host cells. Subtomogram averaging reveals the VAP structure. By heterologous expression of PVAP in cells from all three domains of life, we demonstrate that the protein integrates indiscriminately into virtually any biological membrane, where it forms sevenfold pyramids. We identify the protein domains essential for VAP formation in PVAP truncation mutants by their ability to remodel the cell membrane. Self-assembly of PVAP into pyramids requires at least two different, in-plane and out-of-plane, protein interactions. Our findings allow us to propose a model describing how PVAP arranges to form sevenfold pyramids and suggest how this small, robust protein may be used as a general membrane-remodeling system.Release of virus particles from infected cells is the last essential step of the viral replication cycle. In the course of this process, virions face the challenging task of crossing the cell envelope. Viruses have developed an arsenal of diverse strategies to overcome this problem. Most bacterial viruses are lytic and induce lysis of the infected cell with help of the holin-endolysin system (1), whereas others disrupt the host cell envelope via inhibition of the murein biosynthesis pathway (2). The morphological and genomic properties of archaeal viruses (3) suggested that their egress from host cells may have unusual traits that are different from those of bacterial viruses. Indeed, although most archaeal viruses exit cells without lysis, some, in particular the Sulfolobus islandicus rod-shaped virus 2 (SIRV2) and Sulfolobus turreted icosahedral virus (STIV), are lytic and exploit a special mechanism of virion egress (4–8). During the infection cycle of these viruses, pyramidal protrusions with sevenfold rotational symmetry form in the host cell membrane. As the final step of the infection cycle the virus-associated pyramids (VAPs) open outwards along the seams of their seven facets, creating ∼100-nm apertures through which the newly formed virions escape from the host cell (4, 7). VAPs consist of multiple copies of an ∼10-kDa virus-encoded protein, which we term “PVAP” (Protein forming Virus-Associated Pyramids/SIRV2_P98) (7–9). Surprisingly, PVAP assembles into membrane pyramids even when expressed heterologously in archaeal and bacterial expression systems, demonstrating that no other viral proteins are required for VAP formation (7). The mechanism by which VAPs self-assembles in the membrane remains unknown.In the present study we used electron cryotomography to investigate morphological features of SIRV2 replication and the formation of VAPs at different time points after infection. By subtomogram averaging, we determined a 3D map of the VAP. This map, in combination with secondary structure predictions of PVAP and the expression of wild-type (WT) PVAP or a variety of truncation mutants in archaeal, bacterial and eukaryotic cells allows us to propose a model showing how PVAP arranges to form the sevenfold pyramids. These insights are fundamental for understanding how this mechanism can be exploited as a universal tool to engineer the formation and controlled opening of large pores in biological or artificial lipid bilayers.     

Accessory cardiac bronchus and tracheal bronchus anomalies: CT-bronchoscopy and CT-bronchography findings

Most common developmental anomalies of bronchial tree include accessory cardiac bronchus (ACB) and tracheal bronchus (TB). Minor bronchial anomalies include variants of TB, displaced segmental bronchi, and bronchial agenesis. We present CT-bronchoscopy and CT-bronchography findings of three cases with either ACB or TB. Recognition of these anomalies is important, as associated clinical complications, including recurrent episodes of infection, hemoptysis, and perhaps malignancies may be anticipated in a small percentage of patients.     

The effect of postoperative positive end-expiratory pressure on postoperative bleeding after off-pump coronary artery bypass grafting

Introduction

To compare postoperative prophylactic use of two positive end-expiratory pressure (PEEP) levels in order to prevent postoperative bleeding in patients undergoing off-pump coronary artery bypass grafting (CABG) surgery.

Material and methods

Sixty patients undergoing an elective off-pump CABG operation were included in this prospective, nonrandomized clinical trial. Patients were divided into two groups as receiving either 5 cm H₂O (group 1) or 8 cm H₂O PEEP (group 2) after the operation until being extubated. Chest tube outputs, use of blood products and other fluids, postoperative hemoglobin levels, accumulation of pleural and pericardial fluid after the removal of chest tubes, and duration of hospital stay were recorded and compared.

Results

Low- and high-pressure PEEP groups did not differ with regard to postoperative chest tube outputs, amounts of transfusions and crystalloid/colloid infusion requirements, or postoperative hemoglobin levels. However, low-pressure PEEP application was associated with significantly higher pleural (92 ±37 ml vs. 69 ±29 ml, p = 0.03) and pericardial fluid (17 ±5 ml vs. 14 ±6 ml, p = 0.04) accumulation. On the other hand, high-pressure PEEP application was associated with significantly longer duration of hospitalization (6.25 ±1.21 days vs. 5.25 ±0.91 days, p = 0.03).

Conclusions

Prophylactic administration of postoperative PEEP levels of 8 cm H₂O, although safe, does not seem to reduce chest-tube output or transfusion requirements in off-pump CABG when compared to the lower level of PEEP. Further studies with larger sample sizes are warranted to confirm the benefits and identify ideal levels of PEEP administration in this group of patients.     

Cockroach allergy in a group of Turkish children with respiratory allergies

Exposure to cockroach may lead to exacerbations of bronchial asthma and/or allergic rhinitis in sensitized patients. Although there is a widespread belief that cockroach allergy is a common problem in patients with respiratory allergies, little is known in Turkish children. In order to investigate the prevalence and characteristics of cockroach allergy in respiratory allergic children, we performed a study in newly referred children with respiratory allergies. All patients underwent questionnaire-interview and skin prick tested with common inhalant allergens in addition to two cockroach allergens: Blatella germanica (Bg) and Periplaneta americana (Pa). A subgroup of patients was also serologically investigated for specific IgE against Bg and house dust mite. Three hundred- and thirty-seven children aged 2-16 years were recruited for the study and 77.7% of these were atopic, with the most common indoor and outdoor allergens of house dust mite (47.5%) and grass pollens (45.1%), respectively. According to the prick test results, allergies to Bg and Pa were 11.9% and 7.4%, respectively, and there was a weak correlation between size of the prick test and specific IgE levels for Bg allergen. Almost 30% of the cockroach-sensitive patients were allergic to both cockroach antigens. Seventy percent of cockroach-sensitive patients were also sensitive to house dust mite, and only 1% were monosensitive. Dwellings in the Middle Anatolia and Black Sea regions were less commonly infested by cockroach compared to the dwellings in other regions. In conclusion, our preliminary study showed that cockroach sensitization is common among children with respiratory allergies irrespective of infestation history, suggesting that addition of cockroach allergen to the routine allergy screening panel is critical.