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At least 775 records · Page 43Linked to original sources
PubMed2002

Dietary cholesterol withdrawal reduces vascular inflammation and induces coronary plaque stabilization in miniature pigs.

OBJECTIVE: To study the effect of dietary cholesterol withdrawal on size and composition of LDL-hypercholesterolemia-induced coronary plaques in miniature pigs. METHODS: Pigs were on normal chow (control group), on a cholesterol-rich diet for 37 weeks (hypercholesterolemic group) or on a cholesterol-rich diet followed by normal chow for 26 weeks (cholesterol withdrawal group). Endothelial function was assessed with quantitative angiography after intracoronary infusion of acetylcholine, plaque load with intra-coronary ultrasound and plaque composition with image analysis of cross-sections. The effect of porcine serum on coronary smooth muscle cell (SMC) function was studied in vitro. RESULTS: Cholesterol-rich diet caused LDL-hypercholesterolemia, increased plasma levels of oxidized LDL (ox-LDL) and C-reactive protein (CRP), and induced endothelial dysfunction and coronary atherosclerosis. Dietary cholesterol withdrawal lowered LDL, ox-LDL and CRP. It restored endothelial function, did not affect plaque size but decreased lipid, ox-LDL and macrophage content. Smooth muscle cells and collagen accumulated within the plaque. Increased smoothelin-to-alpha-smooth muscle actin ratio indicated a more differentiated SMC phenotype. Cholesterol lowering reduced proliferation and apoptosis. In vitro, hypercholesterolemic serum increased SMC apoptosis and decreased SMC migration compared to non-hypercholesterolemic serum. CONCLUSIONS: Cholesterol lowering induced coronary plaque stabilization as evidenced by a decrease in lipids, ox-LDL, macrophages, apoptosis and cell proliferation, and an increase in differentiated SMC and collagen. Increased migration and decreased apoptosis of SMC may contribute to the disappearance of the a-cellular core after lipid lowering.

Acetylcholine↗
PubMed2002

Miniaturization of batch- and flow-type chemiluminescence detectors in capillary electrophoresis.

Glass and PTFE tubes as detection cells were put in small light-tight boxes to achieve miniaturization of batch-and flow-type chemiluminescence detectors for capillary electrophoresis. These light-tight boxes which included a detection cell and a photosensor module were successfully designed. In the batch-type detector using a glass tube as a detection cell, the influences of a repeated injection of sample and a reagent volume of the detection cell on chemiluminescence intensity were examined in detail. By using 3.8 mm I.D. glass tube including 400 microl chemiluminescence reagent solution, the chemiluminescence peaks were reproducibly observed for the repeated injection experiment up to the eight injection with each run time of 3.0 min. Dansyl-Trp was determined over the range 3 x 10(-8)-1 x 10(-5) M with the detection limit of 0.43 fmol (S/N=3). In the flow-type detector using a PTFE tube as a detection cell, both ends of the PTFE tube were connected to three-way joints; a chemiluminescence reagent solution was delivered into the cell and a capillary was inserted through one of the joints while an electrode was inserted through the other one. Dansyl-Trp was determined over the range 1 x 10(-7)-1 x 10(-5) M with the detection limit of 1.3 fmol (S/N=3). By using the compact flow-type detector, a mixture of dansyl-amino acids was separated and detected in micellar electrokinetic chromatography mode.

Amino Acids↗
PubMed2002

Polymer-coated synthetic fibers designed for miniaturized sample preparation process.

Miniaturized sample preparation technique for complex sample matrices has been developed with a polymer-coated fibrous extraction medium. Several hundreds of fine fibrous materials were packed longitudinally into a fused-silica capillary followed by a polymeric coating on it to prepare the extraction capillary. The extraction capillary was installed in a liquid chromatograph as a sample loop of the injection valve. The on-line coupled sample preparation/separation system demonstrated a good validity for the analysis of phthalates in real river and wastewater samples. The lowest limits of quantification for several phthalates were less than 1 ng/ml. The effect of polymeric coating to the filaments on the extraction power was also investigated.

Chromatography, High Pressure Liquid↗
PubMed2003

Miniaturized sample preparation combined with liquid phase separations.

Miniaturized sample preparation methods designed as the sample pretreatment for liquid phase separations, such as liquid chromatography, capillary electrophoresis and capillary electrochromatography, have been reviewed especially for the on-line coupling of the sample preparation process and the separation process. The development of the desorption interfaces for the effective combining of the sample preparation and subsequent liquid phase separations is briefly described along with the applications of the combined analytical systems to the analysis of complex sample mixtures such as biological and environmental matrices. Novel use of fine polymeric filaments as the extraction medium for microscale liquid phase separation methods are investigated and a comparison is made with other sample preparation techniques. Polymer coating onto the fibrous material is also introduced to further develop microscale sample preparation methods with improved extraction performance. Several other microscale sample preparation methods having a potential compatibility to the liquid phase separations are also described for future applications of these techniques.

Chromatography, Liquid↗
PubMed2003

Miniaturized on-line proteolysis-capillary liquid chromatography-mass spectrometry for peptide mapping of lactate dehydrogenase.

In this study, methodology was developed for on-line and miniaturized enzymatic digestion with liquid chromatographic (LC) separation and mass spectrometric (MS) detection. A packed capillary LC-MS system was combined with on-line trypsin cleavage of a model protein, lactate dehydrogenase, to provide an efficient system for peptide mapping. The protein was injected onto an enzymatic capillary reactor and the resulting peptides were efficiently trapped on a capillary trapping column. Different trapping columns were evaluated to achieve a high binding capacity for the peptides generated in the enzyme reactor. The peptides were further eluted from the pre-column and separated on an analytical capillary column by a buffer more suitable for the following an electrospray ionisation (ESI) MS process. An important aspect of the on-line approach was the desalting of peptides performed in the trapping column to avoid detrimental signal suppression in the ESI process. The developed on-line system was finally compared to a classical digestion in solution, with reference to peptide sequence coverage and sensitivity. It was shown that the on-line system gave more than 100% higher peptide sequence coverage than traditional digestion methods.

Animals↗
PubMed1991

Hepatic pathology of the colon carcinogen, azoxymethane, in Hanford-Moore miniature pigs.

Azoxymethane (AOM) is commonly used in colon carcinogenesis studies in rodents. In an attempt to develop a large animal model of human colon cancer, AOM was given to Hanford-Moore miniature pigs. Six pigs were injected intraperitoneally with a single dose of AOM of either 5, 10, 20, 40 or 55 mg per kg body weight. Within 48 h, severe signs of toxicity and death occurred in animals receiving greater than 20 mg per kg AOM. After 30 days, all surviving animals were killed and necropsied. Acute hepatic necrosis with haemorrhage was the major toxic effect of AOM in all animals receiving doses exceeding 20 mg per kg. In a second, longer-term experiment, eight pigs were injected with either 20 mg per kg AOM weekly or 10 mg per kg AOM every other week or a combination of both treatments. Chronic toxic effects were limited to the liver. No colon tumours were observed. It is concluded that this particular species demonstrates marked hepatic sensitivity to the toxic effects of AOM.

Animals↗
PubMed2000

Mechanisms of tolerance induction and prevention of cardiac allograft vasculopathy in miniature swine: the effect of augmentation of donor antigen load.

OBJECTIVE: Cotransplantation of a donor kidney along with a heart allograft can induce tolerance to both organs and prevent cardiac allograft vasculopathy in miniature swine. To determine whether the tolerogenic effect of donor kidney cotransplantation was due to an effect specific to the kidney graft or to an increase in donor antigen load, we compared heart-kidney recipients with recipients receiving two class I disparate hearts or with recipients receiving donor peripheral mononuclear cells at the time of isolated heart transplantation. METHODS: Recipients of major histocompatibility complex class I disparate allografts received 12 days of cyclosporine (INN: cyclosporin; 10-13 mg/kg administered intravenously on days 0-11). Group 1 animals received a heart alone (n = 5). Group 2 animals received heart and kidney allografts (n = 4). Group 3 animals received two major histocompatibility complex-matched heart allografts (n = 4). Two double-heart recipients were thymectomized 21 days before transplantation. Group 4 animals received a heart allograft and an infusion of high-dose donor peripheral blood leukocytes (2.5 x 10(9) cells/kg, n = 2). RESULTS: Vasculopathy developed in group 1 recipients and the allografts were rejected within 55 days. Group 2 recipients accepted their heart and kidney allografts indefinitely without vasculopathy. Euthymic recipients from group 3 accepted their hearts long-term (>190 and >197 days), but vascular lesions developed. In thymectomized recipients from group 3, the hearts were rejected in 63 and 96 days with severe vasculopathy. Group 4 recipients demonstrated transient macrochimerism but their hearts were rejected within 47 and 63 days. CONCLUSIONS: The beneficial effects of donor kidney cotransplantation on cardiac allograft survival and prevention of cardiac allograft vasculopathy are likely to involve both an increase in donor antigen load and an effect specific to the kidney allograft.

Animals↗
PubMed1996

Cardiac allograft vasculopathy in partially inbred miniature swine. I. Time course, pathology, and dependence on immune mechanisms.

To assess the role of the immune system in cardiac allograft vasculopathy in large animals, heterotopic heart transplantation was done between partially inbred miniature swine, animals in which transplantation can be done across defined major histocompatibility barriers in a reproducible fashion. Porcine hearts transplanted into untreated recipients across a class I, class II, or full major histocompatibility mismatch were acutely rejected in 6 to 8 days (n = 4). Hearts transplanted into untreated recipients across minor histocompatibility barriers survived for 21 to 44 days (n = 5) and showed no evidence of cardiac allograft vasculopathy. When recipients were treated with a 12-day course of cyclosporine, hearts transplanted across minor histocompatibility barriers survived 42, 64, and 56 days and did not develop vascular lesions. However, hearts transplanted into cyclosporine-treated recipients across a full major histocompatibility disparity survived 20, 22, and 23 days and all three developed biopsy-proven vasculopathy. In one animal, the progression of intimal proliferation was followed in vivo by intracoronary ultrasonography. The degree of intimal thickening documented by ultrasonography correlated well with the intimal proliferation found on tissue histologic samples. These results are the first to show that in large animals, an immune response stimulated by donor major histocompatibility antigens is involved in the induction of cardiac allograft vasculopathy. In addition, these studies point out the utility of a large-animal model of cardiac allograft vasculopathy in which transplantation across defined major histocompatibility barriers can be done reproducibly and in which accurate determinations of the progression or regression of coronary vascular lesions in individual animals can be accurately assessed in vivo.

Animals↗
PubMed1996

Effects of failure of the right side of the heart and increased pulmonary resistance on mechanical circulatory support with use of the miniaturized HIA-VAD displacement pump system.

This experimental study was designed to assess the influence of failure of the right side of the heart or pulmonary hypertension, or both, on the performance of a novel miniaturized left ventricular assist device. In small-sized dogs (n = 50) ischemic global left ventricular failure was induced and support was provided by the HIA-VAD displacement pump (stroke volume 10 or 25 ml) installed as a left ventricular assist device. In three groups of animals (n = 10 each) pulmonary hypertension was created before induction of global left ventricular failure. During left ventricular assist device support temporary ischemic failure of the right side of the heart was induced in four groups of animals (n = 10 each). In the group subjected to left ventricular failure, support with the left ventricular assist device, and right ventricular failure during left ventricular assist, left atrial pressure and cardiac index were significantly lower than in the group subjected to left ventricular failure and left ventricular assist alone (2 +/- 6 versus 11 +/- 6 mm Hg and 1.6 +/- 0.4 versus 1.0 +/- 0.4 L/(min/m2), respectively, p < 0.05). In the group subjected to pulmonary hypertension, left ventricular failure, and left ventricular support, left atrial pressure dropped to values near zero but cardiac index remained unaltered as compared with results with the same regimen without pulmonary hypertension. However, when right ventricular failure was added (that is, pulmonary hypertension, left ventricular failure, left ventricular support, and right ventricular failure during support with the left ventricular assist device) left atrial pressure dropped to negative values (p < 0.05) and cardiac index progressively deteriorated. When, in an additional group of dogs, biventricular support was installed in the latter regimen, circulation was initially well supported but oxygenation deteriorated in 60% of cases. We conclude that (1) adequate right ventricular function was indispensable during support with the left ventricular assist device, (2) the combination of pulmonary hypertension and right ventricular failure led to the "low left ventricular assist device output syndrome," and (3) biventricular mechanical support in the presence of pulmonary hypertension may be complicated by the alveolar leakage syndrome.

Animals↗
PubMed2002

Miniaturization of surface acoustic waves rotary motor.

This paper presents the experimental study of a miniaturized surface acoustic waves (SAWs) rotary motor and the theoretical calculation. After the first success in SAW rotary motor operating at 9.85 MHz, a smaller rotary motor is designed. With the operating frequency of 30 MHz and the driving voltage of 120 V(p-p), the motor can rotate at a speed of 270 rpm.

Acoustics↗
PubMed2004

Motility and penetration competence of frozen-thawed miniature pig spermatozoa are substantially altered by exposure to seminal plasma before freezing.

The objective was to determine if exposure of spermatozoa to seminal plasma before freezing decreases its freezability, assessed by percentage motile cells (using computer-assisted semen analysis) and in vitro penetration ability (using in vitro fertilization and chlortetracycline fluorescence assessment). Ejaculated spermatozoa from miniature pigs were washed by centrifugation within 20 min after collection, then incubated in seminal plasma or modified Hulsenberg VIII diluents (mHM). When the spermatozoa were cryopreserved, spermatozoa incubated in seminal plasma before freezing had significantly lower post-thaw motility than spermatozoa incubated in mHM. The incubation of spermatozoa in seminal plasma also significantly prevented frozen-thawed spermatozoa from penetrating the oocytes. The second experiment, using unfrozen spermatozoa, was to determine if the incubation of spermatozoa with seminal plasma reduced penetration ability before freezing, resulting in a significantly lower penetration rate after freezing (compared with spermatozoa incubated without seminal plasma). The penetration competence of unfrozen spermatozoa was significantly decreased by incubation in seminal plasma, but no difference in motility was observed between spermatozoa exposed to seminal plasma versus mHM. We concluded that ejaculated seminal plasma contained some factor(s) that modified the sperm before freezing and reduced the freezability and post-thaw penetration competence of spermatozoa.

Animals↗
PubMed1997

Recombinant human osteogenic protein-1 induces dentin formation: an experimental study in miniature swine.

It was the aim of the present study to investigate the induction of dentin formation by recombinant human osteogenic protein-1 (hOP-1). In 4 adult miniature pigs a total of 16 teeth with artificially exposed dental pulps were capped with 3 mg of a complex of recombinant hOP-1 in collagen matrix (2.5 micrograms/mg), collagen matrix alone, or calcium hydroxide paste. Teeth were removed in block section after a healing period of 5 weeks. Decalcified sections were processed for light microscopy and histomorphometric analysis. In hOP-1 treated teeth substantial amounts of hard tissue formation (osteodentin and tubular dentin) had consistently led to a complete bridging of the defects. Less dentin formation was seen after calcium hydroxide application. In control defects collagen matrix alone failed to form complete dentin bridges. Recombinant human osteogenic protein-1 in a collagen carrier matrix appeared to be suitable as a bio-active capping agent for surgically exposed dental pulps.

Animals↗
PubMed1990

Scatter photocoagulation restores tissue hypoxia in experimental vasoproliferative microangiopathy in miniature pigs.

Experimental retinal branch vein occlusion using argon laser photocoagulation in miniature pigs induced the development of ischemic retinal territories associated with preretinal neovascularization. Preretinal partial pressure of oxygen (PO2) measurements on the ischemic territories, using O2-sensitive microelectrodes, established that the ischemic retinal areas were hypoxic. Scatter photocoagulation of these ischemic hypoxic territories restores the local PO2 to the normal values within 2 weeks. Hence, the reported inhibitory effect of photocoagulation on the development of retinal neovascularization could be due to a reversal effect on tissue hypoxia.

Animals↗
PubMed1990

Experimental retinal branch vein occlusion in miniature pigs induces local tissue hypoxia and vasoproliferative microangiopathy.

In miniature pigs, retinal veins were experimentally occluded using argon laser coagulation. Microvascular modifications leading to retinal hemorrhages and retinal edema were observed some hours after the occlusion. These lesions resolved progressively within 3 weeks after the occlusion, but in most cases ischemic retinal territories persisted. Preretinal partial pressure of oxygen (PO2) measurements, using double barrelled O2-sensitive microelectrodes, showed that all the ischemic areas were indeed hypoxic. In half of the experiments, preretinal and intravitreal new vessels grew on the ischemic territories. Tissue hypoxia appears to be a key step in triggering neovascularization. However, the critical level of hypoxia was not determined.

Animals↗
PubMed2000

Miniaturized direct on air sampling filter quantification of pollen allergens.

A recently in this journal reported luminescence immunoassay for the direct quantification of birch and grass pollen allergens on air sampling filters. DOSIS, has been miniaturized. By means of a commercially available chlorinated analogue of the previously used 1,2 dioxetane phosphate derivative as enzyme substrate, the air sampling filter diameter could be reduced from 25 mm to 13 mm. The procedure leads to a more than twenty times reduction of the previously reported limit of quantification for the grass pollen allergen.

Air↗
PubMed1996

Immunophenotypic characterization of tumor infiltrating lymphocytes and peripheral blood lymphocytes isolated from melanomatous and non-melanomatous Sinclair miniature swine.

Selectively-bred Sinclair miniature swine exhibit a high incidence of congenital malignant melanoma which either proves fatal (10-15% of tumor-bearing piglets) or spontaneously regresses with a biphasic immunological phenomenon (85-90%) and no recurrence of malignancy. Mononuclear leukocytes were isolated from cutaneous melanomas and peripheral blood specimens collected from melanomatous (tumor-bearing) Sinclair swine during second-phase regression, and from peripheral blood specimens collected from non-melanomatous (tumor-free) Sinclair swine and control Hanford swine. Leukocyte identities were determined with single- and dual-parameter indirect immunofluorescence assays via flow cytometry. Assays for the specific surface antigens CD45, CD2, CD4, CD8, CD1, MHC class II, and N1 were employed to develop immunophenotypic profiles within the gated lymphocyte clusters from each TIL and PBL suspension. Significantly more CD8+ T-lymphocytes were identified in TIL suspensions than in peripheral blood leukocyte (PBL) suspensions (P < and = 0.05), regardless of breed or tumor status. Conversely, PBL suspensions contained significantly higher percentages of CD4+ T-lymphocytes than the levels found in TIL suspensions (P < and = 0.05). Virtually all TIL were MHC class II+, whereas the percentages of PBL expressing this antigen were markedly lower (P < and = 0.05). The percentages of T-lymphocytes co-expressing CD4 and CD8, a normal subset unique to swine, were generally consistent in all TIL and PBL suspensions examined. The results of this study have firmly established the immunophenotypic identities of cells associated with the second-phase regression phenomenon of this melanoma and have identified specific variations in the leukocyte profiles of the respective TIL and PBL suspensions.

Animals↗
PubMed2002

Novel miniaturized systems in high-throughput screening.

High-throughput screening (HTS) using high-density microplates is the primary method for the discovery of novel lead candidate molecules. However, new strategies that eschew 2D microplate technology, including technologies that enable mass screening of targets against large combinatorial libraries, have the potential to greatly increase throughput and decrease unit cost. This review presents an overview of state-of-the-art microplate-based HTS technology and includes a discussion of emerging miniaturized systems for HTS. We focus on new methods of encoding combinatorial libraries that promise throughputs of as many as 100,000 compounds per second.

Combinatorial Chemistry Techniques↗
PubMed2001

Development of a technology for automation and miniaturization of protein crystallization.

The usage of standard 96 well microplates for the screening of crystallization conditions of recombinant proteins offers several advantages when compared to commonly used crystallization plate formats. The adoption of robotic technology for plate and glass slide preparation within a "hanging drop" vapour diffusion crystallization experiment enables to work with an increased throughput at reduced costs. In addition to commercial pipetting devices with a 96-channel aspirator/dispenser, solenoid ink-jet technology was applied to form 250 nl droplets with a diameter of approximately 1 mm. This allows miniaturization of crystallization screening set-ups with an estimated ten-fold cost reduction when compared to commonly used 24 well plates.

Concanavalin A↗