氨基酸腹膜透析液与传统腹膜透析液对腹膜间皮细胞功能的影响

目的通过体外实验对照观察了含氨基酸腹膜透析液(1.1%Nutrineal)和传统葡萄糖腹膜透析液(1.5%Dianeal)对正常人腹膜间皮细胞(HPMC)的生物相容性及功能的影响。方法用1.1%Nutrineal和1.5%Dianeal进行腹膜透析,4h后引流。观察两种不同透出液及不同时间对体外培养的HPMC功能的影响。采用四甲基偶氮多胍(MTT)和细胞直接计数法测定HPMC增殖程度,以测定乳酸脱氢酶(LDH)水平显示细胞损伤程度。采用ELISA法测定白细胞介素6(IL-6)水平。结果与5%葡萄糖对照组相比,1.5%Dianeal透出液可显著降低HPMC细胞增殖能力、细胞总蛋白合成、IL-6分泌水平和细胞黏附能力(P<0.001、P<0.001、P<0.0001、P<0.0001),而细胞培养液上清中的LDH分泌水平明显提高(P<0.001)。1.1%Nutrineal透出液可降低HPMC细胞增殖能力(P<0.001)和明显增加IL-6的分泌水平(P<0.0001),但对HPMC的LDH分泌水平,细胞黏附能力,蛋白总合成量无明显影响。结论与传统的葡萄糖腹膜透析液相比,氨基酸腹膜透析液能更好地维持HPMC在细胞存活能力、细胞黏附功能及蛋白合成等方面的功能。氨基酸腹膜透析液可诱导HPMC分泌IL-6水平显著升高,其机制有待进一步探讨。     

Biological reactions resulting from endotoxin adsorbed on dialysis membrane: an in vitro study

Some types of dialysis membrane are known to adsorb endotoxin (ET). It is suggested that the biocompatibility of dialysis membrane is enhanced by adsorption and inhibition of ET. This study attempts to clarify the membrane-mediated biological reaction of the ET that is adsorbed to a dialysis membrane. After a dialysis circuit was prepared, contaminated dialysate was introduced on the dialysate side of a polyether polymer alloy (PEPA) membrane that adsorbs ET while saline solution or blood were introduced on the blood side, and the difference in ET adsorption between the two set-ups was measured. Further, the side filled with blood was left standing for 2 h, after which the changes in the amount of interleukin 1 receptor antagonist (IL-1Ra) produced from the whole blood were also assayed. Significantly more ET was adsorbed to the dialysis membrane when blood rather than saline was on the other side. In addition, the IL-1Ra production from the dialysis membrane that adsorbed ET was significantly higher. The ET adsorbed to the dialysis membrane may influence a living body even if it does not pass through the membrane. Accordingly, it is difficult to assume that the adsorption of ET to the membrane enhances its biocompatibility.     

Dialyzer Membranes: Effect of Surface Area and Chemical Modification of Cellulose on Complement and Platelet Activation

Using an ex vivo model, the effects of membrane composition and surface area on both the complement system (as reflected by plasma C3a levels) and platelets [as indicated by plasma concentrations of thromboxane B2 (TXB2) and platelet factor 4 (PF4)] were studied. In this model, polyacrylonitrile (PAN) was associated with less complement activation than cuprammonium cellulose (CC). A new "modified cellulose" (MC) membrane, in which a small number of the free hydroxyl groups on cellulose are substituted with a tertiary amino compound, was also associated with a low degree of complement activation, similar to that with PAN. However, the extent of hydroxyl group substitution in four MC membrane subtypes did not correlate with the reduction in complement activation. In studies using CC, the amount of generated C3a correlated with the membrane surface area, although the relationship was curvilinear. Plasma concentrations at the "dialyzer" outlet of TXB2 and PF4 were similar with CC, PAN, and MC. In studies with the MC subtypes, increasing the extent of hydroxyl group substitution paradoxically increased, albeit slightly, the amount of TXB2 generation. In studies with CC, a linear relationship between membrane surface area and TXB2 generation was found. The results suggest a dissociation between platelet and complement effects among different dialyzer membranes, and underline the importance of membrane surface area.     

Extremely high fracture rate of a modular acetabular component with a sandwich polyethylene ceramic insertion for THA: a preliminary report

Improvements of ceramic components and design changes have reduced failure rates over the past 30 years in total hip arthroplasty. We present a series of n = 11 cases with ceramic failure out of n = 113 implantations, from which n = 66 were ceramic-on-ceramic (n = 50 with ceramic insert with sandwich in polyethylene and n = 16 with directly fixed ceramic inlay) and n = 47 ceramic on polyethylene bearings, between 1999 and 2001 after introduction of a new implantation system to the market. The overall fracture rate of ceramic for the whole series (n = 113) was 9.7%. For the combination ceramic head with UHMW-PE (n = 47) the fracture rate was 2.1%. For the combination ceramic with ceramic (n = 66) the fracture rate was 15.2%. For the combination ceramic with ceramic sandwich in PE (n = 50) the failure rate was 18%. Only three patients experienced a trauma. Demography of patients (age, gender, body weight and BMI) was not statistically different between patients with failed ceramics and the rest of the patients making patient-specific risk factors unlikely to be an explanation for the failures. Retrospective X-ray analysis of the cup positioning did not show significant difference between failed and non-failed implants in terms of mean cup inclination and version making also operation-specific factors unlikely to be the only reason of this high failure rate. Therefore, manufacturer-specific factors such as design features may have contributed to this high failure rate. Further analysis of the whole series with biomechanical testing of the retrieved material needs to be performed.     

Electron paramagnetic resonance spectroscopy for the investigation of the fluidity of human spermatozoa plasma membranes: a feasibility study

Spermatozoal membrane perturbations may play a role in abnormal sperm functions. The objective of this investigation was to study the feasibility of measuring membrane fluidity of isolated human sperm by electron paramagnetic resonance (EPR) spectroscopy and to compare the order parameter of spectra obtained from the sperm plasma membranes of living sperm of fertile men with that of infertile men. Ejaculates of infertile and fertile men were washed and the spermatozoa labelled with 5-doxylstearic acid (5-DSA) and 16-doxylstearic-acid (16-DSA) (10 nmol per 4 x 10(7) sperm). The reporter group of 5-DSA partitions into the outer, hydrophilic part of the sperm plasma membrane, whereas that of 16-DSA is distributed in the inner hydrophobic part. The following results were obtained: (i) the lowest measurable cell count was 3.6 to 7 x 10(6) sperm and the interassay variance of the order-parameter s was < 1%; (ii) swim-up experiments revealed a higher fluidity of sperm with a higher percentage of motility; (iii) sperm membranes of infertile patients exhibited a decreased fluidity of their plasma membranes in the polar interface region of 5-DSA compared with volunteer semen donors and fertile men (P=0.002). No difference of membrane fluidity was found between the different groups using 16-DSA. It is concluded that EPR spectroscopy can be used to study the fluidity of sperm plasma membranes in fertile and infertile men.     

A novel application of high-dose (50 kGy) gamma irradiation for demineralized bone matrix: effects on fusion rate in a rat spinal fusion model

BACKGROUND CONTEXT: The safety of allograft material has come under scrutiny because of recent reports of allograft-associated bacterial and viral infections in tissue recipients. Gamma irradiation, although being one of the most effective ways of terminal sterilization, has been shown to affect the biomechanical properties of allograft bone. It may also have detrimental effects on the osteoinductivity of allograft material such as demineralized bone matrix (DBM) by the denaturation of proteins because of heat generated by irradiation. Sterilization of DBM material is an important variable in processing graft materials. This is considered to be one of the factors leading to different fusion rates observed with different commercially available DBM products, as the sterilization procedure itself may affect the osteoinductivity of the material. Currently, there is no ideal sterilization technique that limits the detrimental effect on osteoinductivity and fusion rates. PURPOSE: To evaluate the effects of a range of hydrogen peroxide exposures with or without the controlled high-dose gamma irradiation after processing with radioprotectant solutions (Clearant radiation sterilization procedure) on the fusion rates of human DBM. STUDY DESIGN: A prospective in vivo animal study. METHODS: Eighty mature athymic nude female rats were used for this study, which formed 10 equal groups. Human DBM exposed to hydrogen peroxide for different time periods (0, 1, 6, and 24 hours) was divided into two major subgroups. One group was further treated with controlled high-dose radiation using radioprotectants (radiation treated), whereas the other group was frozen immediately without specific treatment (non-radiation treated). Both radiation-treated and non-radiation-treated DBM material from each group of hydrogen peroxide exposure times were implanted between L4 and L5 transverse processes of the rats forming eight test groups including eight animals in each. The remaining 16 rats were divided into two additional groups to form negative (only decortication, n=8) and positive (bone morphogenetic protein [BMP]-2, n=8) control groups. The rats were evaluated for fusion by radiographs (2, 4, and 8 weeks), manual palpation (8 weeks), and histological analysis after sacrificing. Comparison of fusion rate among all groups was made using these three evaluation methods. RESULTS: Increasing the time period of hydrogen peroxide (0, 1, 6, or 24 hours) exposure for preparation of DBM from bone allograft did not affect the fusion rates significantly (p<.05), although there was a trend toward decreasing fusion rates with longer exposure times. When the hydrogen peroxide washed DBM preparations were also radiation treated, the resulting fusion rates were again not significantly different (p<.05). Agreement among fusion detection methods was found to be high. CONCLUSIONS: Hydrogen peroxide processing was not detrimental to fusion rates. The additional terminal sterilization technique with special gamma irradiation protocols (Clearant process) also did not decrease the fusion rates but could provide an additional margin of safety.     

Virtual reconstruction of paranasal sinuses from CT data: A feasibility study for forensic application

Purpose

The purpose of this study was to report the feasibility of computed modelization and reconstitution of the paranasal sinuses, before and after trauma, from CT data.

Optimizing HIV prevention for women: a review of evidence from microbicide studies and considerations for gender-sensitive microbicide introduction

Introduction

Microbicides were conceptualized as a product that could give women increased agency over HIV prevention. However, gender-related norms and inequalities that place women and girls at risk of acquiring HIV are also likely to affect their ability to use microbicides. Understanding how gendered norms and inequalities may pose obstacles to women''s microbicide use is important to inform product design, microbicide trial implementation and eventually microbicide and other antiretroviral-based prevention programmes. We reviewed published vaginal microbicide studies to identify gender-related factors that are likely to affect microbicide acceptability, access and adherence. We make recommendations on product design, trial implementation, positioning, marketing and delivery of microbicides in a way that takes into account the gender-related norms and inequalities identified in the review.

Methods

We conducted PubMed searches for microbicide studies published in journals between 2000 and 2013. Search terms included trial names (e.g. “MDP301”), microbicide product names (e.g. “BufferGel”), researchers’ names (e.g. “van der Straten”) and other relevant terms (e.g. “microbicide”). We included microbicide clinical trials; surrogate studies in which a vaginal gel, ring or diaphragm was used without an active ingredient; and hypothetical studies in which no product was used. Social and behavioural studies implemented in conjunction with clinical trials and surrogate studies were also included. Although we recognize the importance of rectal microbicides to women, we did not include studies of rectal microbicides, as most of them focused on men who have sex with men. Using a standardized review template, three reviewers read the articles and looked for gender-related findings in key domains (e.g. product acceptability, sexual pleasure, partner communication, microbicide access and adherence).

Results and discussion

The gendered norms, roles and relations that will likely affect women''s ability to access and use microbicides are related to two broad categories: norms regulating women''s and men''s sexuality and power dynamics within intimate relationships. Though norms about women''s and men''s sexuality vary among cultural contexts, women''s sexual behaviour and pleasure are typically less socially acceptable and more restricted than men''s. These norms drive the need for woman-initiated HIV prevention, but also have implications for microbicide acceptability and how they are likely to be used by women of different ages and relationship types. Women''s limited power to negotiate the circumstances of their intimate relationships and sex lives will impact their ability to access and use microbicides. Men''s role in women''s effective microbicide use can range from opposition to non-interference to active support.

Conclusions

Identifying an effective microbicide that women can use consistently is vital to the future of HIV prevention for women. Once such a microbicide is identified and licensed, positioning, marketing and delivering microbicides in a way that takes into account the gendered norms and inequalities we have identified would help maximize access and adherence. It also has the potential to improve communication about sexuality, strengthen relationships between women and men and increase women''s agency over their bodies and their health.     

Impact of prior surgery on the feasibility of laparoscopic surgery for children: a prospective study

Background This study aimed to determine the impact of prior surgery on the feasibility of laparoscopic surgery for children. Methods A prospective study analyzed 471 consecutive children who underwent laparoscopic surgery over a 4-year period. Laparoscopic procedures were classified “easy,” “difficult,” or “demanding.” The end points of the study were conversion rate, intraoperative events, and duration of operation. Results A total of 89 patients (19%) had undergone previous abdominal surgery. The conversion rate was 18% for the patients with prior surgery versus 9% for those without a prior operation (16/89 vs 35/382; p < 0.05). This difference reflects a significantly higher conversion rate for “easy” procedures among patients with than among those without prior surgery, but not for “difficult” and “demanding” procedures. The type of prior surgery had no significant impact on the mean duration of the operation. Of 71 procedures, 12 (17%) after prior conventional surgery were converted, as compared with 4 (22%) of 18 after prior laparoscopy (p > 0.05). Intraoperative events, mainly attributable to adhesions and lack of overview, occurred in 8% of patients with prior procedures, as compared with 2% without former surgery (7/89 vs 9/382; p < 0.05). Relevant complications were not significantly more frequent after prior surgery. The incidence of conversions decreased with increased time between current and previous surgery. It was 64% for surgeries less than 1 year later, 25% for surgeries 1 to 5 years later, and 5% for surgeries more than 5 years later (7/11 vs 6/24 vs 3/54; p < 0.001). Conclusions Prior surgery has a limited impact on the feasibility of laparoscopic surgery for children. The conversion rate and the incidence of intraoperative events, mainly because of adhesions and lack of overviewing, is increased, but not the incidence of relevant complications. The feasibility improves considerably with increased time between surgery and prior surgery. The authors consider laparoscopy to be the first-choice technique after prior surgery.     

Hepatocyte Attachment on Biodegradable Modified Chitosan Membranes: In Vitro Evaluation for the Development of Liver Organoids

Extracellular matrix structures including glycosaminoglycans play a critical role in cell attachment, differentiation, and morphogenesis. We evaluated chitosan ([1 → 4] linked 2-amino-2-deoxy-β- D -glucan) as a biomaterial for hepatocyte attachment because of its structural similarity to glycosaminoglycans. Freshly isolated rat and fetal porcine hepatocytes were seeded on chitosan membranes that had been previously blended with collagen, gelatin, or albumin to improve biocompatibility and surface roughness. The optimal cell density and attachment kinetics were quantified. The metabolic activity was investigated by measuring daily urea and total protein secretion by the cells for 2 weeks. While collagen blended-chitosan membranes provided a good attachment surface for rat hepatocytes, albumin and gelatin blended chitosan membranes were superior for fetal porcine hepatocyte attachment. The optimal attachment was maintained with membranes of medium molecular weight ( M _r = 750,000 daltons) chitosan, at 3–4 × 10 ⁴ cells/cm² after 3 h of incubation. In vitro experiments demonstrated that fetal porcine hepatocytes survived at least 14 days when seeded on the chitosan-albumin matrix, demonstrating that this biomaterial can provide suitable cell attachment scaffolds for creating liver tissue organoids.     

Exclusion of neutropenic children from implanted central venous catheter placement: impact on early catheter removal

Background/Purpose

Based on the known risks of implanted central venous catheter (ICVC) placement in neutropenic children, we instituted a protocol whereby children with hematologic malignancies and an absolute neutrophil count less than 0.5 × 10⁹/L were excluded from an ICVC and had a percutaneously inserted central catheter placed until neutropenia resolved. The impact of this policy on the incidence of ICVC removal within 100 days of placement was evaluated.

Methods

The records of all children with hematologic malignancies who underwent placement of an ICVC (port or cuffed catheter) from 1999 through 2008 were reviewed. The incidence of catheter removal within 100 days was compared between subjects who had ICVC placed before (preprotocol) and after (postprotocol) the absolute neutrophil count-based exclusion protocol.

Results

Implanted central venous catheters were placed in 437 children, 311 in group 1 and 126 in group 2. The incidence of catheter removal within 100 days of placement for infection (4.1% [13/314] versus 0.8% [1/126], P = .07) and all causes combined (9.6% [30/314] versus 2.4% [3/126], P = .01) was substantially lower in the postprotocol group.

Conclusions

We have demonstrated that a protocol whereby neutropenic children were excluded from ICVC placement dramatically diminished complications that necessitated early catheter removal.     

Customized bicarbonate buffered dialysate and replacement solutions for continuous renal replacement therapies: effect of crystallization on the measured levels of electrolytes and buffer

The aim of this study was to investigate the impact of the addition of calcium to bicarbonate solutions for continuous renal replacement therapy (CRRT). We tested single bag (bicarbonate and calcium mixed 24 h before testing) and double bag solutions (mixed immediately before) with and without the addition of 4 mEq/L of acetate. Prescribed calcium varied from 0 to 5 mEq/L. All test solutions containing calcium showed crystallization at light microscopy. The double bag solutions decreased but did not prevent crystallization. The addition of acetate did not interfere with crystallization. Crystallization, as measured by the weight of the crystals after filtration of the solutions, showed a significant positive correlation with the calcium deficit (prescribed minus measured) and with partial pressure of carbon dioxide. The measured level of calcium was lower than expected and correlated with crystallization. Our results suggest that the use of bicarbonate solutions containing calcium as replacement fluids for CRRT is a potentially unsafe procedure.     

Retraction by surface ferromagnetisation of target tissues: Preliminary studies on feasibility of magnetic retraction for endoscopic surgery

BACKGROUND: Magnetic retraction has potential advantages over existing direct physical retraction means (e.g., forceps) in terms of providing complete atraumatic retraction, avoiding tumour cell exfoliation as well as offering the possibility of noncontact retraction. This paper describes a pilot study of surface magnetic retraction of the gastric mucosa to facilitate resection. METHODS: Fifteen porcine stomach specimens were used in this pilot study. The uniaxial tensile properties of retracted mucosa were initially studied using a tensiometer. Magnetic media of ferromagnetic microparticles (stainless steel 410) dispersed in cyanoacrylate liquid were prepared at four different concentrations, and a neodymium permanent magnet was used to magnetically retract the media. The media was finally surface-glued to the target mucosa for performing a simulated surgical procedure. RESULTS: The force measurement data show that the retraction forces increased as the concentrations of microparticles and magnetic media volumes increased. A magnetic media concentration of 2 g/mL was most suitable since it offered sufficient retraction force from a small volume of applied media, e.g., the observed magnetic forces exerted on 50 microL of media were 1.42 N by a 3-mm magnet and 3.75 N by a 6-mm magnet, respectively, both being more than sufficient for the mucosal retraction. The additional forces required for dissection with four alternative instruments, i.e., electrosurgery hook, snares, scalpel or scissors, were also measured, e.g., the total force required to retract up to 10 mm and resect the mucosa with snares was 0.36 +/- 0.17 N. In a simulated surgical procedure (resection of gastric mucosa with glued magnetic medium) retraction by the magnet allowed resection of the tented mucosa by an electrosurgical snare. CONCLUSION: Surface ferromagnetisation of target mucosal tissues could enable magnetic retraction for endoscopic surgery.     

Collagen I membranes for tendon repair: Effect of collagen fiber orientation on cell behavior

Tendons have poor spontaneous regenerative capabilities, and complete regeneration is never achieved despite intensive remodeling. In this in vitro study, we characterized two multilamellar collagen I membranes differing in the arrangement of collagen fiber deposition (oriented vs. nonoriented) and compared their mechanical properties. Human dermal fibroblasts and tenocytes were seeded on the two membranes to evaluate the effect of fiber orientation on cell viability and cytoskeletal organization. Results demonstrate that the multilamellar collagen I membrane with oriented fibers has the better mechanical properties and affords optimum cell proliferation and adhesion. Its fiber arrangement provides an instructive pattern for cell growth and may serve to guide the alignment of cells migrating from the ends of a crushed or frayed tendon to obtain a strong, correctly structured tendon, thus providing a viable clinical option for tendon repair. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 826–832, 2009     

Effects of hypobaric pressure on human skin: feasibility study for port wine stain laser therapy (part I)

BACKGROUND AND OBJECTIVES: Since the development of laser-induced photothermolysis for the therapy of port wine stain (PWS) birthmarks, clinical results have shown that dark purple lesions usually respond well to the first three to five treatments. However, for most PWS, complete blanching is never achieved, and the lesion stabilizes at a red-pink color. The aim of this feasibility study is to demonstrate that with the aid of a local vacuum applied to the lesion site prior to laser exposure, photocoagulation of the smaller PWS blood vessels may be successfully achieved. STUDY DESIGN/MATERIALS AND METHODS: Suction cups were designed to fit onto the hand pieces of commercial laser devices used for PWS laser therapy. One subject with normal skin and another with PWS skin were recruited for this study. Laser pulses of various fluences were applied at atmospheric pressure or shortly after (5-15 seconds) hypobaric pressures (17-51 kPa) were placed as test sites on the forearm of both subjects. The laser-induced purpura at the test sites was documented over the course of 1 week on both subjects and the resulting PWS blanching was optically quantified by visible reflectance spectrometry 7 months after therapy. RESULTS: For the subject with normal skin, the laser fluence needed with hypobaric pressure (51 kPa) to induce similar purpura intensity to that observed with atmospheric pressure was approximately 35% lower. For PWS skin, all suction application times (5-15 seconds) and hypobaric pressures (17-51 kPa) resulted in more intense purpura and the PWS blanching 7 months after treatment was clinically significant for test sites treated with hypobaric pressures ranging from 17 to 34 kPa. CONCLUSIONS: The temporary and controlled dilation of the targeted blood vessels achieved with a local vacuum can significantly reduce the "small-vessel-limitation" in the treatment of PWS without increasing the risk of epidermal damage.     

A commentary from the pioneers on the innovation of the relative motion concept: History,biologic considerations,and anatomic rationale

The relative motion concept is simply recognition of the normal functional anatomic relationships that allow powerful extrinsic muscles, the extensor digitorum communis (EDC) and flexor digitorum profundus (FDP), to vary forces on individual finger joints and function in response to the relative position of adjacent metacarpophalangeal joints (MCPJs) in the hand, one to another. First identified as a cause of complications after surgery, a better understanding now allows us to harness these forces by way of differential metacarpophalangeal joint (MCPJ) positioning using an orthosis. This can reduce undesirable tension and allow immediate controlled active motion while permitting functional use of the hand. Tissue gliding with active motion prevents restrictive scarring, maintains joint mobility and avoids unnecessary limitations and stiffness on normal neighboring structures. The historical development of this concept is shared with explanation of the anatomic and biologic rationale for this approach. Acute and chronic hand conditions that may benefit from better understanding of relative motion are numerous and growing.