Studies on the coupling step in solid phase peptide synthesis. Some preliminary results from competition experiments.
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Alanine↗
Biomedical subjects
S Karlsson
Publications and source records attributed to S Karlsson.
Amino group protection in solid phase peptide synthesis.
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Amino Acids↗
Note on the use of active esters in combination with 1,2,4-triazole in solid phase peptide synthesis.
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Catalysis↗
Retroviral transduction of human CD34+ cells on fibronectin fragment CH-296 is inhibited by high concentrations of vector containing medium.
BACKGROUND: The objective of the present study was to optimize conditions for retroviral transduction of human cord blood (CB) CD34+ cells and to reveal mechanisms which interfere with efficient gene transfer. METHODS: An MSCV based retroviral vector with the gene for enhanced green fluorescent protein (MGIN) produced by GP+envAM12 (amphotropic envelope), PG13 (gibbon ape leukemia virus envelope) or 293GPG (vesicular stomatitis virus envelope) cell lines was used to transduce cord blood CD34+ cells on Retronectin (fibronectin fragment CH-296) in three different ways: either in vector containing medium (VCM), in fresh medium on Retronectin pre-loaded with vector or in VCM on Retronectin pre-loaded with vector. RESULTS: Paradoxically, the transduction efficiency obtained with pre-load of vector onto Retronectin alone was higher than pre-load plus VCM for PG13-MGIN (67.9 +/- 6.0% vs 24.9 +/- 8.0%) and AM12-MGIN (47.5 +/- 5.8% vs 38.7 +/- 2.2%). Further experiments showed that transduction on Retronectin pre-loaded with PG13-MGIN or AM12-MGIN was inhibited by the presence of the same VCM at high concentrations, but not by the presence of a VCM with a different receptor specificity. If no pre-load of vector was performed, the highest transduction efficiencies were seen when VCMs were diluted 1:10 (MOIs of 3). The inhibitory effect of high titer PG13-MGIN VCM was confirmed in more primitive CD34+CD38low cells and in NOD/SCID repopulating cells, and was also seen in experiments with bone marrow CD34+ cells. CONCLUSIONS: Retroviral transduction of CB CD34+ cells on Retronectin is inhibited by high titer PG13 and GP+envAM12 vector containing medium. Efficient gene transfer to human hematopoietic cells can be obtained by preload alone of the vector onto Retronectin. These findings are of importance for the design of transduction protocols for repopulating hematopoietic cells.
Antigens, CD34↗
Ultrasonic diagnosis of occlusion of the celiac axis.
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Aged↗
Contribution of adrenergic nerves and the adrenals to 2-deoxy-D-glucose-induced insulin and glucagon secretion in the mouse.
The contribution of the adrenergic nerves and the adrenals to the increase in plasma levels of insulin, glucagon, and glucose that occurs in response to 2-deoxy-D-glucose (2-DG) was investigated in the mouse. Chemical sympathectomy by 6-hydroxydopamine or adrenalectomy was performed 48 h before intravenous injection of 2-DG (500 mg/kg). In controls, 2-DG increased the plasma levels of insulin, glucagon, and glucose (p less than 0.001). The insulin response to 2-DG was potentiated by adrenalectomy (p less than 0.01), but not affected by chemical sympathectomy. This indicates that the adrenals, but not the adrenergic nerves, restrain the insulin response to 2-DG. In contrast, 2-DG-induced glucagon secretion was partially inhibited by both chemical sympathectomy and adrenalectomy (p less than 0.001). This suggests contribution of both the adrenals and the adrenergic nerves to the glucagon response to 2-DG. Similarly, 2-DG-induced hyperglycemia was inhibited by both adrenalectomy (p less than 0.001) and by chemical sympathectomy (p less than 0.01). We conclude that, in the mouse, 2-DG activates the sympathetic nerves and the adrenals. This activation induces an inhibitory action on insulin secretion, exerted by the adrenals, and a stimulatory action on glucagon secretion, exerted by both the adrenergic nerves and the adrenals.
Adrenal Glands↗
Inhibition of 2-deoxy-glucose-induced glucagon secretion by muscarinic and alpha-adrenoceptor blockade in the mouse.
Neuroglycopenia induced by 2-deoxy-glucose is known to activate the autonomic nervous system and to stimulate glucagon secretion. In this study, the relative contribution of the various branches of the autonomic nervous system on the 2-deoxy-glucose-induced glucagon secretion was investigated in the mouse. An intravenous injection of 2-deoxy-glucose (500 mg/kg) was followed by a 5-fold increase in plasma levels of glucagon (P less than 0.001). This 2-deoxy-glucose-induced glucagon secretion was impaired by pre-treatment with either the muscarinic antagonist methylatropine (by 83%; P less than 0.001) or the nicotinic antagonist hexamethonium (by 90%; P less than 0.001). Further, also the alpha-adrenoceptor antagonist phentolamine inhibited the glucagon response to 2-deoxy-glucose (by 35%; P less than 0.01). In contrast, the beta-adrenoceptor antagonist L-propranolol did not affect the glucagon response to 2-deoxy-glucose. It is concluded that the main mechanism behind the increased plasma levels of glucagon following administration of 2-deoxy-glucose is cholinergic activation. However, intact alpha-adrenoceptors are a pre-requisite for the full effect of 2-deoxy-glucose. In contrast, beta-adrenoceptors seem to be of no importance and there seems to be no room for neuropeptides as mediators of the neuroglycopenia-induced glucagon secretion in the mouse.
Animals↗
Formation of 3,N4-ethenocytidine, 1,N6-ethenoadenosine, and 1,N2-ethenoguanosine in reactions of mucochloric acid with nucleosides.
Mucochloric acid, a genotoxic hydroxyfuranone found in chlorinated drinking water, was reacted with cytidine, adenosine, guanosine, and uridine. HPLC analyses with UV detection at 290 nm showed that one major product peak was formed in the reactions of cytidine, adenosine, and guanosine. The products formed in reactions carried out at 90 degrees C for 24 or 45 h were isolated by HPLC and characterized by 1H and 13C NMR spectroscopy, direct inlet chemical ionization mass spectrometry, and UV absorbance spectroscopy. The structures of the products were assigned to 3,N4-ethenocytidine, 1,N6-ethenoadenosine, and 1,N2-ethenoguanosine. In reactions performed at 37 degrees C and pH 7.0 the same compounds were detected after a reaction time of 7 days. No observable reaction took place between mucochloric acid and uridine.
Adenosine↗
Formation of ethenocarbaldehyde derivatives of adenosine and cytidine in reactions with mucochloric acid.
Mucochloric acid, a genotoxic compound formed during chlorine disinfection of drinking water, was reacted with adenosine and cytidine at pH 4.0, 90 degrees C. HPLC analyses with UV detection at 325 nm showed that one previously unidentified product peak was formed in each reaction. The products were separated and isolated by HPLC and characterized by UV absorbance, 1H and 13C NMR spectroscopy, and mass spectrometry. The products were identified as 3-(beta-D-ribofuranosyl)-7-formylimidazo[2,1-i]purine (I) and 6-(beta-D-ribofuranosyl)-3-formylimidazo[1,2-c]pyrimidin-5(6H)-one (II) (ethenocarbaldehyde derivatives of adenosine and cytidine, respectively). The ethenocarbaldehyde derivative of adenosine was also produced in reactions carried out at pH 7.4 and 37 degrees C. The formation of the ethanocarbaldehyde derivatives and the previously identified etheno derivatives from mucochloric acid is explained by an initial conversion of mucochloric acid, through hydrolysis and decarboxylation, to chloromalonaldehyde. Chloromalonaldehyde reacts with the nucleosides and forms an intermediate adduct which either undergoes ring closure by intramolecular displacement of the chlorine atom or breaks down to form chloroacetaldehyde which subsequently produces the etheno derivatives.
Adenosine↗
Migration of epoxidized soya bean oil from plasticized PVC gaskets into baby food.
Expoxidized soya bean oil (ESBO) is used as a plasticizer in PVC gaskets in lids for glass jars used for packaging of ready-cooked baby food. The migration of ESBO from the lids has been determined in 81 samples of different dishes of baby food, including purées of beef, pork, fish, poultry, berries and vegetables. The level of ESBO in baby food has been determined using a gas chromatography/mass spectrometry (GC/MS) analytical procedure with a detection limit of 1.5 mg/kg. Residues of ESBO were found in all dishes except in blueberries. The levels ranged from < 1.5 to 50.8 mg/kg, with a mean of 11.9 mg/kg and a median of 7.8 mg/kg in food with detectable levels. Expoxidized fatty acids may also occur naturally in food. Baby food which had never been in contact with the lids was therefore analysed and no detectable levels of diepoxidized C18-methylester, which was used for the determination of ESBO, were found. That demonstrates that the presented levels of ESBO in the baby food are only due to migration from the lids and not of natural origin.
Food Contamination↗
Carbon fiber reinforced root canal posts. Mechanical and cytotoxic properties.
The aim of this study was to compare the mechanical properties of a prefabricated root canal post made of carbon fiber reinforced composites (CFRC) with metal posts and to assess the cytotoxic effects elicited. Flexural modulus and ultimate flexural strength was determined by 3 point loading after CRFC posts had been stored either dry or in water. The bending test was carried out with and without preceding thermocycling of the CFRC posts. The cytotoxicity was evaluated by an agar overlay method after dry and wet storage. The values of flexural modulus and ultimate flexural strength were for dry stored CFRC post 82 +/- 6 GPa and 1154 +/- 65 MPa respectively. The flexural values decreased significantly after water storage and after thermocycling. No cytotoxic effects were observed adjacent to any CFRC post. Although fiber reinforced composites may have the potential to replace metals in many clinical situations, additional research is needed to ensure a satisfying life-span.
Animals↗
The proliferation in uterine compartments of intact rats of two different strains exposed to high doses of tamoxifen or toremifene.
Uterine Cell proliferation was studied in intact Sprague-Dawley (SD) and Fischer 344 (F344) rats exposed to the antiestrogens tamoxifen (TAM; 5, 10, 20, or 40 mg/kg) and toremifene (TOR: 21.2 or 42.4 mg/kg). The antiestrogens were administered to animals via gavage daily for 2 or 12 wk. Uterine proliferation was assessed using markers for the proliferating cell nuclear antigen (PCNA) and by the bromodeoxyuridine (BrdU) method. Diethylstilbestrol (DES) was used as an estrogenic reference compound. The antiestrogens either reduced or prevented changes of myometrial and stromal proliferation indices (PI). TAM and TOR caused a time-dependent reduction of endometrial glands without an associated decrease in cell proliferation. In the luminal columnar epithelium, the antiestrogens depressed PCNA PI but enhanced BrdU PI, indicating a low continuous DNA synthesis in otherwise quiescent cells. The antiestrogens induced focal hyperplastic multilayered epithelia with PCNA-positive basal cells along segments of the luminal uterine epithelium. We suggest that this hyperplastic epithelium represents remnants from the glandular epithelium. DES was less efficient in inducing these changes but induced squamous metaplasias in the F344 rats. Uterine effects of the 2 antiestrogens were comparable with the exception of I TAM-exposed (40 mg/kg) SD rat that showed squamous metaplasia. F344 rats were more sensitive to the estrogenic action of DES than were the SD rats.
Animals↗
Fatal thrombo-embolic complications at aorto-femoral angiography.
Fatal complications due to angiographic procedures are rare. An awareness of these complications is, however, mandatory in order to be able to prevent them. This report concerns three fatal cases with a deleterious complication of distal macro- and microembolization in connection with the angiographic procedure. In all cases the local circulation was surgically restored. The microcirculation was 'out of reach' and all three patients succumbed with profound tissue ischemia.
Aged↗
Angiography of the internal mammary artery.
The anatomy and catheterization techniques of the internal mammary artery (i.m.a.) are described. The diagnostic criteria and importance of i.m.a. angiography in thymoma, lymphoma, carcinoma, parathyroid adenoma, diseases of the breast, and trauma are discussed. The role of i.m.a. catheterization for i.a. infusion therapy in lung carcinoma, mesothelioma and chest wall metastases of breast carcinoma and embolization of i.m.a. in bleeding following trauma or tumour ulceration are described. Transcatheter treatment of mediastinal parathyroid adenoma is also described.
Adenoma↗
Impact of implant interdependency when evaluating success rates: a statistical analysis of multicenter results.
PURPOSE: When evaluating the outcome of oral implant treatment, a statistically important aspect to consider is whether any dependency exists among implants placed within the same patient/jaw. If one implant fails, will the risk of subsequent failures increase, i.e., will any of the remaining implants also fail? In an attempt to study this question, the aims of the present study were to statistically determine if the suggested hypothesis was valid, i.e., whether dependency exists among implants in the same patient/jaw, and to determine how failure lifetable analysis should be calculated. MATERIALS AND METHODS: In the present study, multicenter trial material consisting of 1.738 oral implants in 487 patients from 4 separate studies was used. First, any dependency among implants within the same patient/jaw was determined; thereafter, cumulative success rates were calculated for one implant per patient (chosen randomly), and the range of variations in the randomized success rates was also calculated. This was then compared with the cumulative success rates based on the entire material. RESULTS: The statistical analysis showed that a dependency among the implants existed prior to their functional loading, i.e., the risk for an implant failure among the remaining implants in the same patient/jaw increased after the first failure had occurred. CONCLUSION: Both study design and statistical analysis are of importance when comparing success rates from various investigations, since dependency among implants in the same patient/jaw does exist and may influence the success rates. Consequently, it is suggested that only one randomly selected implant from each patient should be considered when calculating implant success rates.
Dental Implantation, Endosseous↗
Factors affecting the shear bond strength of bonded composite inlays.
PURPOSE: This article analyzes the influence of different pretreatments on the bond strength between inlays and the resin cement of three different composite inlay systems: Z-100, Targis, and Art Glass. MATERIALS AND METHODS: Four separate treatments of the composite-bonding agent interface were investigated: (1) untreated surface, (2) grinding, (3) sandblasting, and (4) sandblasting followed by silane treatment. Surface topography, roughness, and shear bond strength were evaluated using digital scanning electron microscopy, confocal laser scanning profilometry, and a Lloyd LRX equipped for shear bond testing, respectively. RESULTS: The bond strength is presented both with respect to composite surface pretreatment and with respect to different composite inlay systems. Independent of the composite inlay system, the sandblasted and silane-treated surface was found to give the highest bond strength values, followed by the sandblasted and ground surfaces. The untreated surface showed the lowest bond strength. For pretreated surfaces, Targis showed the highest (P < 0.05) bond strength values, followed by Art Glass and Z-100. This distribution, however, was reversed for the untreated interface, where Z-100 showed the highest bonding strength (P < 0.05). CONCLUSION: Surface pretreatment and roughness as well as the inlay material have an impact on the bond strength and the retention of composite inlays.
Adhesiveness↗
Water sorption and flexural properties of a composite resin cement.
PURPOSE: The aim of this study was to assess the water sorption and determine the influence of water on flexural properties of a composite resin cement of 2 different viscosities. MATERIALS AND METHODS: A dual-cured composite resin cement of 2 different viscosities was tested according to International Standards Organization standards for dental composite materials. The samples tested for water sorption were stored in distilled water for 7 or 60 days. The samples tested for flexural properties were divided into 2 groups and stored either wet in distilled water or dry for 1, 7, or 60 days. After storage, a flexural test was performed with 3-point bending equipment. RESULTS: A significant increase in water sorption for both viscosities was registered as the storage time increased, but no significant difference between the 2 viscosities was recorded. Significantly lower strength and modulus were found for specimens that were wet stored for 60 days compared with the dry-stored ones, and significant changes in deflection at break were also registered. There were no differences in flexural properties between the 2 viscosities. Because of the lubricant and plasticizing effect of water on composite resin materials, the secant modulus and deflection at break seem to be valid methods to describe the complete deflection behavior. CONCLUSION: Water has an important effect on the flexural properties of composite resin cement after 60 days of storage time. No significant differences in water sorption and flexural properties were found between the high and low viscosities of the composite resin cement studied.
Absorption↗
On a new method to assess the accuracy of a CAD program.
PURPOSE: This study was initiated with the purpose of developing and evaluating a system for measuring the magnitude of the variation between a computer-aided design (CAD) object created on the computer screen and a replicated object produced by computer-aided manufacturing (CAM). MATERIALS AND METHODS: Controlled geometric forms, a square and a cone, were designed in a CAD program, and measuring distances were selected. The CAD data were transmitted to CAM data, and objects were produced. The CAD/CAM process was the Procera system, and the holder system permitted the objects to be ground into cross sections, similar to the visualization in the CAD program. Five objects of each shape were produced and measured by two operators two times. Three operators measured one of the objects 30 times. RESULTS: Observed values were greater than the true value. For all objects, the systematic error was at most 15.5 microns. Interoperator difference was small. The variation because of measurement error was greater for the square object compared to the cone. However, the variation because of object was higher for the cone object than for the square. The total standard deviation was 7.7 microns. Thus, the total random error caused by object variation and measurement error was in approximately 95% of all measurements less than 15 microns. CONCLUSION: There are no differences in the measurement data derived from this method and actual measurement data from an object created by the computer-aided dental design program. The method has high validity and reliability, i.e., high accuracy.
Analysis of Variance↗