Archive of Medical Research

Poly(ethylene imine)-g-chitosan using EX-810 as a spacer for nonviral gene delivery vectors.

Polyelectrolyte complexes have been widely studied as gene carriers in recent years. In this study, poly (ethylene imine) was grafted onto chitosan (PEI-g-CHI) as a nonviral gene carrier in order to improve the water solubility as well as the inherent transfection efficiency of chitosan. We present a novel method to conjugate the amine or hydroxyl groups of chitosan (CHI) and the amine groups of PEI through opening the epoxide rings of ethylene glycol diglycidyl ether (EX-810), which also brings the merits as mentioned in PEGylation chemistry. The degree of substitution of PEI onto CHI was characterized by NMR. The preliminarily cellular mechanisms, from the cellular entry to the endosomal release, were investigated by the correlations among the physicochemical properties of the DNA-polymer complexes, the buffering capacity of the modified polymer, the cytotoxicity, and the efficiency of the transgene expression. The cytotoxicity assayed by MTT shows that cell viability of PEI-g-CHI is higher than CHI especially noticeable at high concentrations using human kidney 293T cells. The efficiency of transgene expression and the amount of intracellular plasmid were monitored using green fluorescent protein (GFP) and visualized by fluorescence microscopy. The transfection efficiency of PEI-g-CHI/DNA polyplex is significantly better than CHI/DNA polyplex when using the weight ratios higher than 2.5. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Lou YL, Peng YS, Chen BH, Wang LF, Leong KW.

Faculty of Medicinal and Applied Chemistry, School of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan 80708, Republic of China.

Evaluation of the mechanical properties of posterolateral structures and supporting posterolateral instability of the knee.

The objectives of this study are to evaluate the contributions of the popliteofibular ligament (PFL), the popliteus tendon (PT), and the lateral (fibular) collateral ligament (LCL) to the posterolateral stability of the knee by changing the sequence of selective transection. Twelve fresh-frozen cadaveric knees were divided into two groups. Group 1 has a cutting sequence as follows: PFL, PT, LCL. Group 2 has a cutting sequence as follows: PT, PFL, LCL. Each specimen was mounted on the apparatuses using the Ilizarov external fixator for measuring external rotatory and varus laxities at every 30 degrees from 0 degrees to 90 degrees of knee flexion. In both groups, there was no significant difference between the PFL and PT in the increment of respective external rotatory laxity after transection at each knee flexion angle, except 0 degrees in group 2. The transection of the LCL significantly increased the external rotation laxity at 0 degrees and 30 degrees . Varus instability was increased significantly only after cutting the LCL at every knee flexion angle. In conclusion, both the PFL and PT equally contribute to the external rotatory stability. The LCL also contributes to the external rotatory stability at early range of knee flexion. The LCL is a main structure for varus stability in the knee. (c) 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Chun YM, Kim SJ, Kim HS.

Department of Orthopaedic Surgery, Anthroscopy and Joint Research Institute, Yonsei University College of Medicine, CPO Box 8044, 134, Shinchon‐dong, Seodaemun‐gu, Seoul 120‐752, Korea.

Interview with President Shirley Tilghman (Princeton University).

The reality and importance of founder speciation in evolution.

A founder event occurs when a new population is established from a small number of individuals drawn from a large ancestral population. Mayr proposed that genetic drift in an isolated founder population could alter the selective forces in an epistatic system, an observation supported by recent studies. Carson argued that a period of relaxed selection could occur when a founder population is in an open ecological niche, allowing rapid population growth after the founder event. Selectable genetic variation can actually increase during this founder-flush phase due to recombination, enhanced survival of advantageous mutations, and the conversion of non-additive genetic variance into additive variance in an epistatic system, another empirically confirmed prediction. Templeton combined the theories of Mayr and Carson with population genetic models to predict the conditions under which founder events can contribute to speciation, and these predictions are strongly confirmed by the empirical literature. Much of the criticism of founder speciation is based upon equating founder speciation to an adaptive peak shift opposed by selection. However, Mayr, Carson and Templeton all modeled a positive interaction of selection and drift, and Templeton showed that founder speciation is incompatible with peak-shift conditions. Although rare, founder speciation can have a disproportionate importance in adaptive innovation and radiation, and examples are given to show that \”rare\” does not mean \”unimportant\” in evolution. Founder speciation also interacts with other speciation mechanisms such that a speciation event is not a one-dimensional process due to either selection alone or drift alone. BioEssays 30:470-479, 2008. (c) 2008 Wiley Periodicals, Inc.

Templeton AR.

Department of Biology, Washington University, St. Louis, Missouri 63130‐4899.

Thromboprophylaxis for patients with cancer and central venous catheters: a systematic review and a meta-analysis.

BACKGROUND.: Central venous catheter (CVC) placement increases the risk of thrombosis and subsequent death in patients with cancer. The objective of this systematic review was to determine the efficacy and safety of anticoagulation in reducing mortality and thromboembolic events in cancer patients with a CVC. METHODS.: The authors searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and ISI the Web of Science databases. They included randomized controlled trials in patients with cancer comparing unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), vitamin K antagonists, fondaparinux, or ximelagatran with no intervention, placebo, or each other. The standard methods of the Cochrane Collaboration were used for the analyses. RESULTS.: Of 3986 identified citations we included 9 randomized clinical trials, none of which evaluated fondaparinux or ximelagatran. Heparin therapy (UFH or LMWH) was associated with a trend toward a reduction in symptomatic deep venous thrombosis (DVT) (relative risk (RR), 0.43; 95% confidence interval (95% CI), 0.18-1.06), but there was no statistically significant effect on mortality (RR, 0.74; 95% CI, 0.40-1.36), infection (RR, 0.91; 95% CI, 0.36-2.28), major bleeding (RR, 0.68; 95% CI, 0.10-4.78), or thrombocytopenia (RR, 0.85; 95% CI, 0.49-1.46). The effect of warfarin on symptomatic DVT also was not statistically significant (RR, 0.62; 95% CI, 0.30-1.27). CONCLUSIONS.: The balance of benefits and downsides of thromboprophylaxis in cancer patients with CVC are uncertain. Clinicians together with their patients must weigh these factors carefully when making decisions regarding thromboprophylaxis. Cancer 2008. (c) 2008 American Cancer Society.

Akl EA, Kamath G, Yosuico V, Kim SY, Barba M, Sperati F, Cook DJ, Schünemann HJ.

Department of Medicine, State University of New York at Buffalo, Buffalo, New York.

Perlecan, the \”jack of all trades\” proteoglycan of cartilaginous weight-bearing connective tissues.

Perlecan is a ubiquitous proteoglycan of basement membrane and vascularized tissues but is also present in articular cartilage, meniscus and intervertebral disc, which are devoid of basement membrane and predominantly avascular. It is a prominent pericellular proteoglycan in the transitory matrix of the cartilaginous rudiments that develop into components of diarthrodial joints and the axial skeleton, and it forms intricate perichondrial vessel networks that define the presumptive articulating surfaces of developing joints and line the cartilage canals in cartilaginous rudiments. Such vessels have roles in the nutrition of the expanding cell numbers in the developing joint. Perlecan sequesters a number of growth factors pericellularly (FGFs, PDGF, VEGF and CTGF) and through these promotes cell signalling, cell proliferation and differentiation. Perlecan also interacts with a diverse range of extracellular matrix proteins, stabilising and organising the ECM, and promoting collagen fibrillogenesis. Perlecan is a prominent pericellular component of mesenchymal cells from their earliest developmental stages through to maturation, forming cell-cell and cell-ECM interconnections that are suggestive of a role in mechanosensory processes important to tissue homeostasis. BioEssays 30:457-469, 2008. (c) 2008 Wiley Periodicals, Inc.

Melrose J, Hayes AJ, Whitelock JM, Little CB.

Raymond Purves Research Laboratories, Institute of Bone and Joint Research, Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, NSW, Australia.

In vivo knee loading characteristics during activities of daily living as measured by an instrumented total knee replacement.

We examined the relationship between activity, peak load, medial to lateral load distribution, and flexion angle at peak load for activities of daily living. An instrumented knee prosthesis was used to measure knee joint force simultaneously with motion capture during walking, chair sit to stand and stand to sit, stair ascending and descending, squatting from a standing position, and golf swings. The maximum total compressive load at the knee was highest during stair ascending and descending and lowest during rising from a chair. Maximum total compressive load occurred at substantially different flexion angles ranging from 8.5 degrees during walking to 91.8 degrees during squatting. For all activities, total compressive load exceeded 2 times body weight, and for most activities 2.5 times body weight. Most activities placed a greater load on the medial compartment than the lateral compartment. Activities were grouped into three categories: high cycle loading (walk), high load (stair ascent, descent, and golf), and high flexion angle (chair sit to stand/stand to sit, and squat). The results demonstrate that the forces and motion sustained by the knee are highly activity-dependent and that the unique loading characteristics for specific activities should be considered for the design of functional and robust total knee replacements, as well as for rehabilitation programs for patients with knee osteoarthritis or following total knee arthroplasty. (c) 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Mündermann A, Dyrby CO, D\’Lima DD, Colwell CW Jr, Andriacchi TP.

Department of Mechanical Engineering, Durand Building 205, 496 Lomita Mall, Stanford University, Stanford, California 94305‐4038.

Increased Postprandial Triglyceride-Rich Lipoprotein Levels in Elderly Survivors of Myocardial Infarction.

Postprandial triglyceride-rich lipoproteins (TRL) levels are a predictor for coronary atherosclerosis. The aim of the study was to compare fasting high density lipoprotein (HDL) cholesterol, plasma lipoprotein lipase (LPL) activity, and postprandial TRL between elderly survivors of myocardial infarction (MI) and healthy controls. A case-control study was performed in 44 elderly patients 65-85 years of age with a previous history of MI and 43 age- and sex-matched healthy controls. Each participant underwent physical examination and was given a standard oral fat load with subsequent blood sampling over the next 8 h. Total and chylomicron triglycerides were assessed by area under the curve (AUC), incremental are under the curve (AUCi) and triglyceride response (TGR). Elderly MI patients had significantly lower postheparin LPL activity (87.4 +/- 36.9 mU/ml) (mean +/- 1 SD) than healthy controls (106.0 +/- 29.0 mU/ml) (P = 0.014). Decreased postheparin LPL activity was accompanied by significant increased and delayed clearance of postprandial TRL. Fasting HDL cholesterol was significantly lower in elderly MI patients than controls (1.45 +/- 0.32 and 1.66 +/- 0.47 mmol/l, respectively, P = 0.048). Multiple regression analysis revealed postheparin LPL activity as an independent predictor for postprandial TRL and fasting HDL cholesterol. Logistic regressions analysis revealed HDL cholesterol, triglycerides measured 2 h after the oral fat load, and postheparin LPL activity as independent predictors for MI. Our findings indicate that decreased fasting HDL cholesterol is associated with increased postprandial triglyceridemia which could be a target for life-style and therapeutic interventions in patients at risk for cardiovascular disease.

Lekhal S, Børvik T, Nordøy A, Hansen JB.

Center for Atherothrombotic Research in Tromsø, Department of Medicine, Institute of Clinical Medicine, University of Tromsø, 9037, Tromsø, Norway, samira.lekhal@fagmed.uit.no.

Seawater requirement for the production of lipoxazolidinones by marine actinomycete strain NPS8920.

A novel marine actinomycete strain NPS8920 produces a new class of 4-oxazolidinone antibiotics lipoxazolidinone A, B and C. Lipoxazolidinone A possesses good potency (1-2 mug/mL) against drug-resistant pathogens methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). Strain NPS8920 exhibits different morphologies in both agar and submerged cultures. The ability of strain NPS8920 to sporulate on saline-based agar media but not on deionized water-based agar medium supported that strain NPS8920 is a marine actinomycete. While strain NPS8920 does not require seawater for growth, the production of lipoxazolidinones by strain NPS8920 can only be detected in the seawater-based media. The optimal production of lipoxazolidinones was observed in the natural seawater-based medium. Strain NPS8920 produced 10-20% of lipoxazolidinones in the synthetic sea salt Instant Ocean((R))-based medium and no production in the sodium chloride-based and deionized water-based media.

Sunga MJ, Teisan S, Tsueng G, Macherla VR, Lam KS.

Nereus Pharmaceuticals, Inc, 10480 Wateridge Circle, San Diego, CA, 92121, United States.

Development of a stable continuous flow immobilized enzyme reactor for the hydrolysis of inulin.

A 23.5-fold purified exoinulinase with a specific activity of 413 IU/mg and covalently immobilized on Duolite A568 has been used for the development of a continuous flow immobilized enzyme reactor for the hydrolysis of inulin. In a packed bed reactor containing 72 IU of exoinulinase from Kluyveromyces marxianus YS-1, inulin solution (5%, pH 5.5) with a flow rate of 4 mL/h was completely hydrolyzed at 55 degrees C. The reactor was run continuously for 75 days and its experimental half-life was 72 days under the optimized operational conditions. The volumetric productivity and fructose yield of the reactor were 44.5 g reducing sugars/L/h and 53.3 g/L, respectively. The hydrolyzed product was a mixture of fructose (95.8%) and glucose (4.2%) having an average fructose/glucose ratio of 24. An attempt has also been made to substitute pure inulin with raw Asparagus racemosus inulin to determine the operational stability of the developed reactor. The system remained operational only for 11 days, where 85.9% hydrolysis of raw inulin was achieved.

Singh RS, Dhaliwal R, Puri M.

Carbohydrate and Protein Biotechnology Laboratory, Department of Biotechnology, Punjabi University, Patiala, 147 002, Punjab, India, rssingh11@lycos.com.