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PubMed2003

Acceleration of cartilage repair by genetically modified chondrocytes over expressing bone morphogenetic protein-7.

BACKGROUND: Cartilage has a limited capacity to heal. Although chondrocyte transplantation is a useful therapeutic strategy, the repair process can be lengthy. Previously we have shown that over expression of bone morphogenetic protein-7 (BMP-7) in chondrocytes by adenovirus-mediated gene transfer leads to increased matrix synthesis and cartilage-like tissue formation in vitro. In this context we hypothesized that implantation of genetically modified chondrocytes expressing BMP-7 would accelerate the formation of hyaline-like repair tissue in an equine model of cartilage defect repair. METHODS: Chondrocytes treated with adenovirus vector encoding BMP-7 (AdBMP-7) or as control, an adenovirus vector encoding an irrelevant gene (Escherichia coli cytosine deaminase, AdCD) were implanted into extensive (15 mm diameter) articular cartilage defects in the patellofemoral joints of 10 horses. Biopsies were performed to evaluate early healing at 4 weeks. At the terminal time point of 8 months, repairs were assessed for morphology, MRI appearance, compressive strength, biochemical composition and persistence of implanted cells. RESULTS: Four weeks after surgery AdBMP-7-treated repairs showed an increased level of BMP-7 expression and accelerated healing, with markedly more hyaline-like morphology than control. Quantitative real-time polymerase chain reaction (PCR) analysis of the repair tissue 8 months after surgery showed that few implanted cells persisted. By this time, the controls had healed similarly to the AdBMP-7-treated defects, and no difference was detected in the morphologic, biochemical or biomechanical properties of the repair tissues from the two treatment groups. CONCLUSIONS: Implantation of genetically modified chondrocytes expressing BMP-7 accelerates the appearance of hyaline-like repair tissue in experimental cartilage defects. CLINICAL RELEVANCE: Rehabilitation after cell-based cartilage repair can be prolonged, leading to decreased patient productivity and quality of life. This study shows the feasibility of using genetically modified chondrocytes to accelerate cartilage healing.

Adenoviridae↗

PubMed2003

Accelerated rehabilitation after arthroscopic Bankart repair for selected cases: a prospective randomized clinical study.

PURPOSE: Increased stress within a certain limit enhances ligament healing and improves joint function. In this prospective randomized clinical trial, we compared the clinical results of early motion versus conventional immobilization after arthroscopic Bankart repair in a selected patient population. TYPE OF STUDY: Prospective randomized clinical trial. METHODS: We performed an arthroscopic Bankart repair using suture anchors in 62 patients with traumatic recurrent anterior instability of the shoulder. Patients were randomized into 2 groups; group 1 (28 patients; mean age, 28 years) was managed with 3 weeks of immobilization using an abduction sling and conventional rehabilitation program, and group 2 (34 patients; mean age, 29 years) was managed with an accelerated rehabilitation program that consisted of staged range of motion and strengthening exercises from the immediate postoperative day. Selection criteria were nonathletes with recurrent anterior shoulder dislocation and a classic Bankart lesion with a robust labrum limited to 1 cm from the midglenoid notch. The patients were followed up for a mean of 31 months (range, 27 to 45 months; standard deviation, 9 months). Analysis of outcome included pain scores at 6 weeks and at final follow-up evaluation, range of motion, return to activity, recurrence rate, patient satisfaction with each rehabilitation program, and shoulder scores assessed by the American Shoulder and Elbow Surgeons Shoulder Index, the rating system of the University of California at Los Angeles, and another scoring system. RESULTS: The recurrence rate was not different between the 2 groups (P =.842). None of the groups developed recurrent dislocation. Two patients from each group were positive for anterior apprehension signs. Patients who underwent accelerated rehabilitation resumed functional range of motion faster (P <.001) and returned earlier to the functional level of activity (P <.001). Accelerated rehabilitation decreased postoperative pain (P =.013), and more patients were satisfied with this program (P <.001). Shoulder scores, return to activity, pain score, and range of motion were not different between the 2 groups at the final follow-up evaluation (P >.05). CONCLUSIONS: Early mobilization of the operated shoulder after arthroscopic Bankart repair does not increase the recurrence rate in a selected group of patients. Although the final outcomes are approximately the same for both groups, the accelerated rehabilitation program promotes functional recovery and reduces postoperative pain, which allows patients an early return to desired activities.

Adolescent↗

PubMed1998

Malononitrilamides 715 and 279 prevent accelerated cardiac allograft rejection synergistically with cyclosporin A in presensitized rats.

A77 1726 is a malononitrilarnide (MNA) and the active metabolite of leflunomide. Leflunomide has been extensively investigated and shown to be a potent immunosuppressive drug. However, the half-life of A77 1726 is about 15-18 days in humans and the leflunomide is, therefore, currently being evaluated for the treatment of autoimmune disease and not for transplantation. The search for analogues has led to the development of MNA 715 and 279, derivatives of A77 1726. Previous limited experimental experience has shown these MNAs to prevent skin allograft and xenograft rejection and graft-versus-host disease in rodents, and to reverse ongoing allograft rejection. The aim of the present study was to verify the efficacy of these MNAs in a cardiac retransplant model of sensitized rats, concerning prevention of accelerated rejection, inhibition of antibody production and interaction with cyclosporin A (CsA). Heterotopic cardiac transplantation and retransplantation in Dark Agouti (DA) to Piebald Virol Glaxo (PVG) rats was used. Subgroups of rats were given either CsA, MNA 715, MNA 279 or combined CsA/MNA for 10 days starting either day 0 or day -1, as of regrafting or no treatment. Titres of allospecific IgM and IgG were quantitated by flow cytometry. Ten days of MNA 715 or 279 from day -1 prevented accelerated rejection of the retransplant, as did CsA. Neither treatment given from day 0 prevented rejection within 24 h. However, a combination of MNA 715 or 279 and CsA from day 0 effectively prevented accelerated regraft rejection. Production of specific alloantibodies was reduced in all immunosuppressed subgroups, IgG titres at day 7 in MNA-treated subgroups being significantly lower compared with those in the CsA-treated subgroup. In conclusion, MNA 715 and 279 were shown to be potent immunosuppressants with the capacity to prevent accelerated regraft rejection in rat cardiac transplants, most efficiently in combination with CsA, and to suppress specific alloantibody production.

Alkynes↗

PubMedDate not supplied

The combination of high-accelerator epoxy resin and antigen retrieval to obtain more intense immunolabeling on epoxy sections than on LR-white sections for large proteins.

The purpose of this study was to examine how antigen retrieval affected the yield of immunogold labeling on epoxy sections based on embedding with different amounts of accelerator. The concentration of accelerator DMP-30 (tri(dimethyl amino methyl) phenol) was varied in the range of 0-8% in the processing of the tissue for epoxy embedding. Immunogold labeling was performed on epoxy sections and LR-White sections of fibrin clots and renal tissue with IgG-deposits, and the antibodies used were anti-fibrinogen anti-IgG and, respectively. For some of the sections antigen retrieval was performed by heating the sections in citrate buffer. In all cases, the yield of immunogold labeling increased following antigen retrieval. The increase (%) in the yield of immunogold labeling as a result of antigen retrieval was larger for epoxy sections than for LR-White sections. The immunolabeling on high-accelerator epoxy sections exposed to antigen retrieval was about 20% more intense than on untreated LR-White sections both for IgG and fibrinogen. In addition to breaking fixations bonds introduced by the chemical fixation, we believe that the antigen retrieval also breaks bonds between the epoxy resin and the embedded tissue. The combination of increased amount of accelerator during tissue processing for epoxy embedding and antigen retrieval by heating in citrate buffer is a potent method for increasing specific immunolabeling on epoxy sections.

Acrylic Resins↗

PubMedDate not supplied

Gadolinium-based contrast and carbon dioxide angiography to evaluate renal transplants for vascular causes of renal insufficiency and accelerated hypertension.

PURPOSE: To evaluate the utility and potential nephrotoxicity of gadolinium-based contrast angiography when used with carbon dioxide angiography in renal transplant patients with suspected vascular causes of renal insufficiency and/or accelerated hypertension. MATERIALS AND METHODS: Thirteen consecutive renal transplant patients with suspected vascular causes of renal insufficiency and/or accelerated hypertension were evaluated with gadolinium-based contrast and CO2 angiography with use of digital subtraction techniques. Stenotic lesions were treated with angioplasty with/or without stent placement. No iodinated contrast agents were used. Serum creatinine levels were obtained before and at 24 and 48 hours after the procedure. An increase in creatinine levels greater than 0.5 mg/dL (44 micromol/L) was considered significant. RESULTS: Nine patients were studied for renal insufficiency, two for accelerated hypertension, and two for both. All 13 studies were considered diagnostic. Significant stenoses were treated in four patients with angioplasty with or without stent placement. Two patients had progression of their renal insufficiency. One of these patients underwent biopsy and was found to have both acute and chronic rejection. The other patient underwent cardiac catheterization 2 days after a transplant renal artery angioplasty. In the remaining nine patients with renal insufficiency (creatinine range, 1.8-3.9 mg/dL [159-345 micromol/L]; mean, 2.7 mg/dL [239 micromol/L]), renal function improved or did not worsen. CONCLUSION: Based on this limited study, gadolinium-based contrast angiography appears to be a promising supplement to CO2 angiography for the diagnosis and treatment of vascular lesions in patients with renal transplant insufficiency and/or accelerated hypertension. Further study is necessary to determine safety, optimal gadolinium dosage, and imaging parameters.

Acute Disease↗

PubMed1997

In vivo determination of drug kinetic linearity and individual organ elimination by the accelerated infusion technique.

The objectives of this study were to (1) establish a controlled drug input method, accelerated infusion, for pharmacokinetic analysis in animals and (2) use the accelerated infusion method to determine the biological barriers responsible for the low oral bioavailability of a peptidic compound in rats. The method involves the administration of an infusion at flow rates which increase linearly with time, that is, accelerated infusion (AI). The accuracy of the system in delivering AIs was tested by comparing the observed volumes with the expected volumes. For experiments with the peptidic compound, a solution was administered by AI into the systemic circulation of rats via the carotid artery (IA). The pharmacokinetic linearity of the compound was determined from the linear phase of the concentration-time curve with the systemic clearance (CLs) calculated from the slope of the linear phase. Solutions of the peptidic compound were administered into the portal vein (IPV) or the inferior vena cava (IVC) by AI to assess the hepatic and pulmonary contribution to elimination. AIs into the duodenum (ID) assessed the roles of permeability and metabolism on the absorption of the peptidic compound across the intestinal mucosa. The system was reliable in delivering the desired AI in vitro. The pharmacokinetics of the peptidic compound in rats was linear up to 17 micrograms/ml in blood. Systemic clearance (CLs) of total compound in blood was calculated to be 31 ml/min/kg. Above 17 micrograms/ml, drug concentrations showed an upward deviation from linearity, indicating loss of linearity due to saturation of elimination. Plasma concentration-time profiles for IPV, IVC, and IA infusions were not substantially different. Our conclusions can be summarized as follows: (1) Accelerated infusion is a valuable, reliable approach that can be used to assess pharmacokinetics linearity, first-pass metabolism, and bioavailability. (2) The peptidic compound has a broad, linear kinetic range in rats, and nonlinearity at high concentration is due to saturation of elimination. (3) The compound has low first-pass elimination in the intestinal mucosa, liver, and lung. (4) The factor that determines the oral bioavailability in rats of the peptidic compound used in this study is mucosal permeability.

Animals↗

PubMed1999

A unique urinary constituent, 6-hydroxy-6-methyl-3-heptanone, is a pheromone that accelerates puberty in female mice.

BACKGROUND: Olfactorily mediated puberty acceleration in female mice (measured by an increase in uterine weight) has been observed since the 1960s without the active chemosignal being structurally identified. There are many controversies in the literature as to whether this male-originated pheromone is a volatile substance. We investigated the chemical nature of the urinary fractions that are responsible for the characteristic uterine weight increases. RESULTS: The active pheromone was identified as 5,5-dimethyl-2-ethyltetrahydrofuran-2-ol and/or its open-chain tautomer (6-hydroxy-6-methyl-3-heptanone). A series of cyclic vinyl ethers were isolated from chromatographically active fractions of the urine. Because these compounds did not accelerate puberty, we postulated that these ethers were degradation products of a lactol (5,5-dimethyl-2-ethyltetrahydrofuran-2-ol). The lactol was then detected directly in the mouse urine extract using a silylation agent. Synthetic 6-hydroxy-6-methyl-3-heptanone had strong biological activity, whereas its close structural analogs did not. CONCLUSIONS: The male house mouse excretes into its urine a large quantity of a volatile substance that has a unique lactol/hydroxyketone structure. This substance is capable of binding to the less volatile urinary constituents, such as proteins or peptides, and is active in puberty-acceleration bioassays. The controversies regarding the volatility of the puberty-accelerating pheromones can now be explained by considering a complex of volatile lactol/hydroxyketone and urinary proteins.

Animals↗

PubMed2003

Accelerated degradation of HMG CoA reductase mediated by binding of insig-1 to its sterol-sensing domain.

Sterols accelerate degradation of the ER enzyme 3-hydroxy-3-methylglutaryl CoA reductase (HMG CoA reductase), which catalyzes a rate-controlling step in cholesterol biosynthesis. This degradation contributes to feedback inhibition of synthesis of cholesterol and nonsterol isoprenoids. Here, we show that degradation of HMG CoA reductase is accelerated by the sterol-induced binding of its sterol-sensing domain to the ER protein insig-1. Accelerated degradation is inhibited by overexpression of the sterol-sensing domain of SREBP cleavage-activating protein (SCAP), suggesting that both proteins bind to the same site on insig-1. Whereas insig-1 binding to SCAP leads to ER retention, insig-1 binding to HMG CoA reductase leads to accelerated degradation that is blocked by proteasome inhibitors. Insig-1 appears to play an essential role in the sterol-mediated trafficking of two proteins with sterol-sensing domains, HMG CoA reductase and SCAP.

Animals↗

PubMedDate not supplied

[Alternating chemotherapy and hyperfractionated accelerated radiotherapy in non-metastatic inflammatory breast cancer].

PURPOSE: Based on encouraging results reported in alternating radiotherapy and chemotherapy in inflammatory breast carcinoma, we have tried in this study to optimize locoregional treatment with a hyperfractionated accelerated radiotherapy schedule alternating with chemotherapy. PATIENTS AND METHODS: From May 1991 to May 1995, 54 patients, previously untreated, with non-metastatic inflammatory breast cancer were entered in an alternating protocol consisting of eight courses of combined chemotherapy and two series of loco-regional hyperfractionated accelerated radiotherapy with a total dose of 66 Gy. Hyperfractionated accelerated radiotherapy was started after three courses of neoadjuvant chemotherapy (Adriamycin, Vincristine, Cyclophosphamide, Methotrexate, 5-fluoro-uracile) administered every 21 days +/- G.CSF. The first series delivered 45 Gy/three weeks to the breast, the axillary, subclavicular and internal mammary nodes, with two daily sessions of 1.5 Gy separated by an interval of eight hours; the second series consisted of a boost (21 Gy/14 fractions/10 d) alternating with another regimen of anthracycline-based-chemotherapy (a total of five cycles every three weeks). Hormonal treatment was given to all patients. RESULTS: Of the 53 patients evaluated at the end of the treatment, 44 (83%) had a complete clinical response, seven (13%) had a partial response (> 50%) and two (4%) had tumoral progression. Of the 51 patients who were locally controlled, 18 (35%) presented a locoregional recurrence (LRR); eight (15%) had to undergo a mastectomy. All the patients but two with LRR developed metastases or died of local progressive disease and 26 (50%) developed metastases. With a median follow-up of 39 months (range: 4-74 months), survival rates at three and five years were respectively, 66 and 45% for overall survival and 45 and 36% for disease-free survival. CONCLUSION: Alternating a combination of chemotherapy and hyperfractionated accelerated radiotherapy is a well-tolerated regimen which provides acceptable local control. The systemic dissemination remains the major problem of inflammatory breast carcinoma and further clinical trials using alternative drug regimens are warranted.

Adenocarcinoma↗

PubMed1993

An engineered disulfide cross-link accelerates the refolding rate of calcium-free subtilisin by 850-fold.

The mature form of subtilisin is an unusual example of a monomeric protein with a high kinetic barrier to folding and unfolding. Using site-directed mutagenesis of subtilisin BPN', we are attempting to determine the physical and energetic nature of the kinetic barrier. The high-affinity calcium-binding site A has been shown to create a large enthalpic barrier to unfolding. Removing the calcium-binding site A from subtilisin by deleting amino acids 75-83 greatly accelerates both unfolding and refolding reactions. Here a disulfide cross-link is introduced between residues 22 and 87 in delta 75-83 subtilisin. This was done to probe the conformational entropy of the transition state for folding. The 1.8-A X-ray structure of this mutant and the effects of the cross-link on the kinetics of unfolding and refolding are reported. Consistent with an expected loss of entropy of the unfolded protein due to the cross-link, the disulfide accelerates folding relative to the uncross-linked form. The magnitude of the acceleration of folding rate (700-850-fold at 25 degrees C) indicates that residues 22 and 87 are ordered in the transition state such that the disulfide does not affect its total entropy. Although early organization of structure around amino acids 22 and 87 greatly accelerates folding, we do not know whether the early folding of this region is a highly populated folding pathway in the absence of the cross-link. The slow step in the delta 75-83 subtilisin folding reaction may be forming initial structures capable of propagating the folding reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗

PubMed2000

The C-terminal domain of nucleolin accelerates nucleic acid annealing.

We report that the abundant nucleolar protein nucleolin accelerates nucleic acid annealing. Nucleolin accelerates annealing of complementary oligonucleotides and of oligonucleotides that contain a limited number of mismatches. The annealing activity of nucleolin can be localized to a C-terminal region consisting of two RNA binding domains (RBD3 and RBD4) and the RGG(9) domain (RBD3-RBD4-RGG(9)). This same region mediates self-association of nucleolin. The RGG(9) domain of nucleolin, believed to mediate interactions between nucleolin and several ribosomal proteins, is neither sufficient for self-association, as determined by small-angle X-ray scattering, nor can it independently accelerate annealing. Acceleration of nucleic acid annealing by nucleolin is likely to depend on self-association of nucleolin molecules bound to nucleic acid.

Animals↗

PubMed2006

Dramatic acceleration of the pd-catalyzed [4+2] benzannulation reaction of enynes and diynes in the presence of lewis acids and bases: expanded scope and new mechanistic insights.

Dramatic acceleration of the palladium catalyzed [4+2] benzannulation and sequential [2+2+2] trimerization reactions in the presence of a Lewis acid/phosphine combination or in the presence of Bronsted bases has been explored. These novel sets of conditions allowed for remarkable enhancement of reaction rates and broadening of the substrate scope and for a significant improvement of reaction yields, particularly for problematic pentasubstituted benzenes. It was found that the real nature of Lewis acid acceleration does not only lie in the isomerization of conjugated enynes but also in the direct acceleration of the [4+2] benzannulation reaction. These experimental findings, combined with the deuterium-labeling studies and DFT calculations, led to a mechanistic rationale, which (a) reasonably accounts for the observed acceleration of the reaction by Lewis acid and bases; (b) provides a viable alternative route for the ring-closing step in the mechanism of benzannulation; (c) clarifies the mechanism of hydrogen migration; and (d) for the first time provides a rationale for the origins of the remarkable stereoselectivity of the hydrogen migration during the benzannulation reaction.

Journal Article↗

PubMed2005

Free radical generation assays: new methodology for accelerated oxidation studies at low temperature in complex food matrices.

A novel method for the rapid screening of antioxidant efficacy and oxidative stability in food and feed matrices has been developed. The analyses are described as free radical generation (FRG) assays. The new procedure combines the use of azo-initiators with analytical equipment that is widely used for antioxidant research such as the oxidative stability instrument and the oxygen bomb. The use of initiators instead of high temperatures as a driving force to increase the rate of oxidation improves the correlation between the accelerated screening of foodstuffs and real shelf life. The improved correlation can be mainly explained by the fact that food products are analyzed in their original status, maintaining all interfacial phenomena of the food matrix. Furthermore, the lower temperature of analysis reduces differences between the reaction kinetics of the assay and those of the oxidation during actual shelf life. Consequently, the correlation between the accelerated analysis and shelf life is improved, particularly when compared to accelerated oxidation at high temperatures. The FRG assays could be used successfully to evaluate the efficacy of natural antioxidants in heat-sensitive food products such as emulsions and meat products. A good correlation was observed between the accelerated tests and the oxidation parameters obtained from standard shelf-life evaluation. It was possible to successfully compare the efficacy of several antioxidants and to predict shelf life for these heat-sensitive food matrices.

Animals↗

PubMed1999

Response of the aroma fraction in sherry wines subjected to accelerated biological aging.

The effect of an acceleration assay, carried out with a periodic aeration and an increased surface/volume ratio, on various aroma compounds of "fino" Sherry wines aging under a veil of a pure culture of Saccharomyces cerevisiae race capensis G1 flor film yeast was studied. The results were subjected to multifactor analysis of variance, and the compounds simultaneously depending on acceleration conditions and aging time at p < 0.01 were subjected to principal component analysis. The first component, accounting for 86.14% of the overall variance, was mainly defined by acetaldehyde and its derivatives 1,1-diethoxyethane and acetoin. These compounds reached higher concentrations in accelerated aging wines in a shorter time than they did in control wines, and no browning problems were detected. Taking into account that these compounds can be used as indicators for biological aging of "fino" Sherry wines, the acceleration condition assayed can be applied to shorten the time of this process.

Alcohols↗

PubMed2002

Rate acceleration of the Baylis-Hillman reaction in polar solvents (water and formamide). Dominant role of hydrogen bonding, not hydrophobic effects, is implicated.

A substantial acceleration of the Baylis-Hillman reaction between cyclohexenone and benzaldehyde has been observed when the reaction is conducted in water. Several different amine catalysts were tested, and as with reactions conducted in the absence of solvent, 3-hydroxyquinuclidine was found to be the optimum catalyst in terms of rate. The reaction has been extended to other aldehyde electrophiles including pivaldehyde. Attempts to extend this work to acrylates was only partially successful as rapid hydrolysis of methyl and ethyl acrylates occurred under the base-catalyzed and water-promoted conditions. However, tert-butyl acrylates were sufficiently stable to couple with relatively reactive electrophiles. Further studies on the use of polar solvents revealed that formamide also provided significant acceleration and the use of 5 equiv of formamide (optimum amount) gave faster rates than reactions conducted in water. Using formamide, further acceleration was achieved in the presence of Yb(OTf)(3) (5 mol %). The scope of the new conditions was tested with a range of Michael acceptors and benzaldehyde and with a range of electrophiles and ethyl acrylate. The origin of the rate acceleration is discussed.

Journal Article↗

PubMed1996

Solvent Effects on a Diels-Alder Reaction Involving a Cationic Diene: Consequences of the Absence of Hydrogen-Bond Interactions for Accelerations in Aqueous Media.

In order to study the influence of hydrogen-bond interactions on the accelerations of Diels-Alder reactions in water and highly aqueous mixed solvent systems, second-order rate constants for the Diels-Alder reaction of acridizinium bromide (1a) with cyclopentadiene (CP) have been measured in aqueous media and organic solvents. Only modest rate accelerations were found in water-rich media. This is attributed to the absence of hydrogen-bonding groups in the reactants. Comparison with cycloadditions of CP with 9-carbomethoxyacridizinium bromide (1b), acrylonitrile (3), and methyl vinyl ketone (4), which do contain hydrogen-bond acceptors, reveals substantially larger aqueous accelerations. These results demonstrate that hydrogen bonding is a major factor in aqueous accelerations. Also rate constants for the cycloaddition of CP to 1a in surfactant solutions were determined. Micellar catalysis is observed in SDS solutions, due to binding of both the diene and the dienophile to the anionic micellar surface.

Journal Article↗

PubMed2006

On the application of accelerated molecular dynamics to liquid water simulations.

Our group recently proposed a robust bias potential function that can be used in an efficient all-atom accelerated molecular dynamics (MD) approach to simulate the transition of high energy barriers without any advance knowledge of the potential-energy landscape. The main idea is to modify the potential-energy surface by adding a bias, or boost, potential in regions close to the local minima, such that all transitions rates are increased. By applying the accelerated MD simulation method to liquid water, we observed that this new simulation technique accelerates the molecular motion without losing its microscopic structure and equilibrium properties. Our results showed that the application of a small boost energy on the potential-energy surface significantly reduces the statistical inefficiency of the simulation while keeping all the other calculated properties unchanged. On the other hand, although aggressive acceleration of the dynamics simulation increases the self-diffusion coefficient of water molecules greatly and dramatically reduces the correlation time of the simulation, configurations representative of the true structure of liquid water are poorly sampled. Our results also showed the strength and robustness of this simulation technique, which confirm this approach as a very useful and promising tool to extend the time scale of the all-atom simulations of biological system with explicit solvent models. However, we should keep in mind that there is a compromise between the strength of the boost applied in the simulation and the reproduction of the ensemble average properties.

Algorithms↗

PubMed2001

Intestinal transit in dogs is accelerated by volume distension during fat-induced jejunal brake.

Intestinal transit is accelerated by volume distension and slowed by nutrient load. We hypothesized that the accelerating effect of volume distension might overcome the slowing effect of nutrient. To test this hypothesis, we compared intestinal transit in five dogs equipped with duodenal and mid-intestinal fistulas. The proximal half of the small intestine was perfused with 60 mM oleate, while the distal half of the small intestine was either perfused with buffer (with distension) or left unperfused (without distension). We found that intestinal transit was slowed by oleate (with marker recovery reduced from 85.8 +/- 5.3 to 39.4 +/- 7.5%) (P < 0.01) and that volume distension accelerated intestinal transit so that marker recovery increased from 39.4 +/- 7.5 without distension to 60.8 +/- 6.3% with distension (P < 0.05). We concluded that intestinal transit is accelerated by volume distension during fat-induced jejunal brake.

Animals↗