bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of mast cell sensitization by chemical allergens: A comparative study
Authors: Holliday M. R. , Coleman J. W. , Dearman R. J. , Kimber I. 
Published: October 2006

AbstractIn previous investigations we have shown that chemical allergens of different classes induce in mice qualitatively divergent immune responses. Respiratory allergens provoke substantial increases in total serum concentration of IgE. In contrast, contact allergens which are known or suspected not to cause respiratory sensitization or which at most have only a very limited potential to do so, have little or no effect on total serum IgE. Such differences, we propose, provide a novel approach for the prospective identification of chemicals with potential to cause respiratory allergy. In the absence of a robust method for the direct measurement of respiratory hypersensitivity reactions in mice we have sought in the present study to determine whether the IgE responses induced in mice by respiratory allergens are specific and of sufficient magnitude to cause the active sensitization of mast cells in vivo, a prerequisite for immediate hypersensitivity, including acute‐onset respiratory hypersensitivity. Topical exposure of BALB/c mice to concentrations of ≥ 10% of the human respiratory allergen trimellitic anhydride (TMA) caused the specific sensitization of peritoneal mast cells in situ as measured by the conjugate‐induced release of [3H]‐5‐hydroxytryptamine in vitro. Experiments were performed also with 2,4‐dinitrochlorobenzene (DNCB), a contact allergen that fails to induce respiratory hypersensitivity. Treatment of mice with concentrations of DNCB of comparable immunogenicity failed to cause mast cell sensitization. These data demonstrate that a known human chemical respiratory allergen induces in mice specific mast‐cell‐sensitizing IgE antibody and reinforce the value of the mouse as a model for the evaluation of respiratory sensitization potential.
Delayed neurotoxic effect of sarin in mice after repeated inhalation exposure
Authors: Husain K. , Vijayaraghavan R. , Pant S. C. , Raza S. K. , Pandey K. S. 
Published: October 2006

AbstractDelayed neurotoxicity of sarin in mice after repeated inhalation exposure has been studied. Female exposed to atmospheric sarin (5 mg m−3 for 20 min) daily for 10 days developed muscular weakness of the limbs and slight ataxia on the 14th day after the start of the exposure. These changes were accompanied by significant inhibition of neurotoxic esterase (NTE) activity in the brain, spinal cord and platelets. Histopathology of the spinal cord of exposed animals showed focal axonal degeneration. These changes were comparatively less than in animals treated with the neurotoxic organophosphate, mipafox. Results from this study indicate that sarin may induce delayed neurotoxic effects in mice following repeated inhalation exposure.
Effects of disulfiram on serum Dopamine‐β‐hydroxylase and blood carbon disulphide concentrations in alcoholics
Authors: Caroldi Stefano , Paris Paola De , Zotti Sergio , Zanella Ilia , Brugnone Francesco 
Published: October 2006

AbstractThe aim of this study was to investigate the effects of single and repeated disulfiram doses on serum dopamine‐β‐hydroxylase activity and blood carbon disulphide concentrations in a group of abstinent alcoholics. The increase in the blood concentration of carbon disulphide was dose dependent after the oral administration of 100–400 mg of disulfiram. Free carbon disulphide peaked at 12 h while the protein‐bound fraction increased at least up to 24 h. Both single (100–400 mg p.o.) and repeated (200 mg daily p.o. for ca. 1 month) administrations failed to inhibit the activity of serum dopamine‐β‐hydroxylase. The repeated daily administration of 200 mg of disulfiram also had no influence on copper‐activated serum dopamine‐β‐hydroxylase, which was the same before and after 1‐month treatment period. Contrary to the disulfiram group, the activity of the copper‐activated enzyme in the serum of abstinent alcoholics declined significantly during the same 30 days.
Modulation of ricin toxicity in mice by biologically active substances
Authors: Muldoon D. F. , Stohs S. J. 
Published: October 2006

AbstractRicin is a highly toxic protein produced by the castor bean (Ricinus communis). It is one of various protein toxins that consist of two subunits joined by a disulfide bridge. One chain facilitates entry of the toxin into the cell while the other chain exhibits RNA N‐glycosidase activity, which attacks a specific site on 28S rRNA, preventing polypeptide elongation and leading to cell death. Although ricin and other protein toxins are potential health hazards, no antidote against these toxins exists. Thus, a number of selected compounds were screened for their ability to alter ricin lethality in mice, based on percentage survival and time to death following a ricin LD100 of 25 μg kg−1 i.p. While no compound tested prevented lethality, dexamethasone and difluoromethylornithine (DFMO) significantly extended survival time. The effects of DFMO on ricin toxicity were markedly influenced by altering various pharmacokinetic parameters. The antioxidants butylated hydroxyanisole and vitamin E succinate also extended survival time in response to a lethal dose of ricin, but to a lesser extent than did dexamethasone and DFMO. The Golgi apparatus inhibitors monensin, swainsonine and tunicamycin enhanced ricin toxicity, as evidenced by shortened survival times. In addition, various nucleoside analogs, including acyclovir and trifluridine as well as adenosine, guanosine and dibutyryl cyclic AMP, also potentiated the toxity of ricin. The results demonstrate that the toxicity of ricin is modulated by a wide variety of structurally distinct chemicals and may involve different mechanisms. Furthermore, the extent and direction of the modulation of ricin toxicity is highly dependent upon pharmacokinetic variables, including dose and dosing interval.
Hemolysis and deformability of erythrocytes exposed to butoxyacetic acid, a metabolite of 2‐Butoxyethanol: I. Sensitivity in rats and resistance in normal humans
Authors: Udden Mark M. , Patton Cynthia S. 
Published: October 2006

AbstractThe effects of butoxyacetic acid (BAA), a metabolite of the important solvent 2‐butoxyethanol, on rat and human red blood cells (RBCs) were investigated. Rat RBCs demonstrated decreased deformability as assessed by a sensitive polycarbonate sieve filtration technique and an increased mean cellular volume after incubation with 0.2 and 2.0 mM BAA for 1–4 h. Evaluation of erythrocyte morphology showed that rat RBCs exposed to BAA became spherocytic and lysed to form erythrocyte membrane ghosts. Hemolysis of rat erythrocytes was rapid in 2.0 mM BAA. Changes in the deformability of rat erythrocytes appear to precede hemolysis. Treated rat erythrocytes also demonstrated a tendency to agglutinate and to release hemoglobin, which formed visible precipitates. None of the adverse effects seen in the RBCs of rats were observed in human blood similarly incubated with 2.0 mM BAA.
Proposed protocols for the determination of potential ocular effects of organophosphorus pesticides
Authors: Hamernik Karen L. 
Published: October 2006

AbstractThe US Environmental Protection Agency now requires ocular toxicity testing to support the registration of organophosphorus pesticides. As a first step toward guideline development for the conduct of these studies, preliminary protocols for ocular toxicity testing in the non‐rodent and rodent are being proposed by the Office of Pesticide Programs. Proposed protocol parameters include determination of animal health status, measurement of plasma, erythrocyte and retinal cholinesterase activities, ocular assessment by routine ophthalmological examination, slit lamp biomicroscopy, fundic observations, tonometry, electroretinography and determination of objective refractivity, pupillary response and tracking. Gross and detailed histopathological examinations of ocular system components would also be conducted. Associated questions and concerns with regard to ocular toxicity testing are presented. The Agency plans to hold a workshop in the near future to discuss issues related to protocol refinement and guideline development.
Effects of organophosphates on the visual system of rats
Authors: Boyes William K. , Padilla Stephanic , Tandon Pushpa , Barone Stan 
Published: October 2006

AbstractThe possibility that exposure to organophosphate insecticides can lead to ocular damage is suggested by Japanese studies from the 1960s and 1970s indicating that exposed humans developed chronic ocular degeneration, in addition to showing more commonly accepted effects of cholinesterase‐inhibiting compounds. Other papers reported ocular lesions in laboratory animals treated with organophosphates. More recently, retinal degeneration following chronic organophosphate treatment has been reported to the Environmental Protection Agency by pesticide manufacturers in studies conducted in compliance with good laboratory practice regulations. Several factors, however, have prompted scepticism regarding organophosphate‐induced ocular toxicity, including the widespread use of organophosphate compounds for both agricultural and ophthalmological practices without numerous additional reports of comparable ocular toxicity. We are developing a research program to address these issues involving electrophysiological, biochemical and histological investigations of rats treated with organophosphate insecticides. The research program is young, but early results are available. Notably, retinas from rats treated with a single subcutaneous injection of 100 mg kg−1 fenthion showed decreases in carbachol‐stimulated release of inositol phosphate, an indicator of cholinergically‐mediated intracellular second messenger systems. These effects persisted at least 56 days after fenthion administration. This could indicate several different toxicological actions, which are currently under investigation. It is concluded that the possible association between exposure to organophosphates and ocular toxicity cannot be dismissed, and that several important research issues need to be resolved.
Effects of collagen fiber orientation on the response of biologically derived soft tissue biomaterials to cyclic loading
Authors: Sellaro Tiffany L. , Hildebrand Daniel , Lu Qijin , Vyavahare Naren , Scott Michael , Sacks Michael S. 
Published: October 2006

AbstractIn the present study, the effects of initial collagen fiber orientation on the medium‐term (up to 50 × 106 cycles) fatigue response of heart valve soft tissue biomaterials was investigated. Glutaraldehyde treated bovine pericardium (GLBP), preselected for uniform structure and collagen fiber orientation, was used as the representative heart valve biomaterial. Using specialized instrumentation, GLBP specimens were subjected to cyclic tensile loading to maximum stress levels of 500 ± 50 kPa at a frequency of 22 Hz. Two sample groups were examined, one with the preferred collagen fiber direction parallel (PD) and perpendicular (XD) to the direction of applied strain. The primary findings indicated that GLBP fatigue response was highly sensitive to the direction of loading with respect to fiber orientation. Specifically, when loading perpendicular to the preferred collagen fiber orientation, fiber reorientation is the dominant mechanism. In contrast, when loaded parallel to the preferred fiber direction a reduction in both collagen fiber crimp and fiber reorientation occurred. Moreover, alterations in the degree and direction of mechanical anisotropy can be inducted by cyclic loading when specimens are loaded perpendicular to the preferred fiber direction. Fourier Transform Infrared Spectroscopy (FT‐IR) results indicate that molecular‐level damage to collagen occurs in both groups after only 20 × 106 cycles. Taken as a whole, the results of this study suggest that initial collagen orientation plays a critical role in bioprosthetic heart valve biomaterial fatigue response. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
The effect of zoledronic acid incorporated in a poly(D,L‐lactide) implant coating on osteoblasts in vitro
Authors: Greiner S. , Kadow‐Romacker A. , Lübberstedt M. , Schmidmaier G. , Wildemann B. 
Published: October 2006

AbstractBisphosphonates such as zoledronic acid (ZOL) are used in diseases associated with osteoclast‐mediated bone loss. However, their antiresorptive activity is partly due to their effect on osteoblasts. Local application might increase the therapeutical fence and their local efficiency and reduce systemic side effects. Aim of the study was to investigate the effect of ZOL on human osteoblasts like cells in vitro with special focus on the synthesis of factors mediating osteoclast differentiation (RANKL, OPG). ZOL was incorporated in an implant coating based on poly(D,L‐lactide) (PDLLA) in different concentrations (10–150 μM). Control groups were treated with uncoated implants, PDLLA‐coated implants, and ZOL pure substance in corresponding concentrations. After an experimental period of 144 h, primary human osteoblasts were stained with alamar blue and cell viability was measured. Procollagen I synthesis, osteoprotegerin (OPG) secretion, and soluble receptor activator of nuclear factor‐κB ligand (sRANKL) were analyzed. Results showed that cell viability was not affected when treated with doses equivalent up to 100 μM ZOL‐coated implants (ZOL‐CI). Procollagen I synthesis was highest when treated with 50 μM ZOL‐CI. OPG increased significantly in the 10 μM ZOL‐CI group, whereas sRANKL decreased significantly with different concentrations of ZOL‐CI. Higher concentrations or exposure to the pure substance showed a decrease in cell viability, collagen I, OPG, and sRANKL synthesis. In conclusion, exposure to specific concentrations of ZOL‐CI showed a beneficial effect on osteoblast differentiation and protein synthesis without influencing their proliferation. Changes in sRANKL and OPG production may contribute to the inhibition of osteoclastic bone resorption. This local antiresorptive effect might be clinically useful in osseous implant integration and fracture healing. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Friction of total hip replacements with different bearings and loading conditions
Authors: Brockett Claire , Williams Sophie , Jin Zhongmin , Isaac Graham , Fisher John 
Published: October 2006

AbstractMetal‐on‐ultra‐high molecular weight polyethylene (UHMWPE) total hip replacements have been the most popular and clinically successful implants to date. However, it is well documented that the wear debris from these prostheses contributes to osteolysis and ultimate failure of the prosthesis, hence alternative materials have been sought. A range of 28 mm diameter bearings were investigated using a hip friction simulator, including conventional material combinations such as metal‐on‐UHWMPE, ceramic‐on‐ceramic (CoC), and metal‐on‐metal (MoM), as well as novel ceramic‐on‐metal (CoM) pairings. Studies were performed under different swing‐phase load and lubricant conditions. The friction factors were lowest in the ceramic bearings, with the CoC bearing having the lowest friction factor in all conditions. CoM bearings also had low friction factors compared with MoM, and the trends were similar to CoC bearings for all test conditions. Increasing swing phase load was shown to cause an increase in friction factor in all tests. Increased serum concentration resulted in increased friction factor in all material combinations, except MoM, where increased serum concentration produced a significant reduction in friction factor. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Synthesis of carboxy‐labelled l‐carnitine
Authors: Goodfellow Donald B. , Hoppel Charles L. , Turkaly Julia S. 
Published: October 2006

AbstractA method for the production of carboxy‐labelled l‐carnitine is described. The first step is the chemical synthesis of 4‐N‐trimethylammoniobutanoate (butyrobetaine) from the precursors 4‐aminobutanoate and iodomethane. The second step involves the hydroxylation of butyrobetaine to form l‐carnitine using butyrobetaine hydroxylase partially purified from bovine calf liver. The method also can be used to synthesize Me‐labelled and uniformly‐chain‐labelled l‐carnitine.
18O labeled nucleosides. 1. A general method for the synthesis of specifically labeled pyrimidine deoxyribosides
Authors: Schram Karl H. , Ratcliff Steven , Neenan John 
Published: October 2006

AbstractA facile method for the preparation of 18O labeled pyrimidine deoxyribosides is described. The method provides a means of selectively labeling the base, sugar or both the base and sugar moieties with high levels of 18O. Thymidine is used as a model to illustrate the method. The site and level of label was established using mass spectrometry.
Synthesis of 13C‐labelled medroxyprogesterone acetate with three 13C isotopes [1]
Authors: Rao P. Narasimha , Damodaran Kalyani M. 
Published: October 2006

Abstract17α‐Hydroxyprogesterone (2) was converted to an enol‐lactone 8 in which the 20‐oxo group was selectively protected as an ethylene acetal. The enol‐lactone 8 was subjected to Claisen condensation with phenl acetate‐1,2‐13C2 in the presence of sodium hydride, which on subsequent treatment with a mixture of acetic acid and hydrochloric acid followed by acetylation gave 17α‐acetoxyprogesterone‐3,4‐13C2 (9). The enol‐ether 10 obtained from 9 was treated with tetrabromomethane‐13C, in pyridine‐dioxane solution, to give the 6‐dibromomethylene derivative 11, Which was then hydrogenated to yield finally 17α‐acetoxy‐6α‐methyl‐13C‐pregn‐4‐ene‐3,20‐dione‐3,4‐13C2 (12).
Synthesis of 2‐bromo‐[1‐14C]ethanamine hydrobromide
Authors: Bach Peter H. , Bridges James W. 
Published: October 2006

Abstract2‐Bromo‐[1‐14C]ethanamine hydrobromide (BEA) was synthesized from [2‐14C]ethan‐1‐01‐2‐amine hydrochloride, by reaction with HBr in a specially designed chamber at an elevated temperature. The synthetic product was purified in the reaction chamber by fractional vacuum sublimation to give a yield of up to 90% of BEA having a purity greater than 95%.
Preparation of [2α‐14CH3]‐dihydrotestosterone 17‐propionate
Authors: Parnes Howard , Pease John 
Published: October 2006

AbstractAn efficient preparation of a very large quantity (650 mCi) of [2α‐14CH3]‐dihydrotestosterone 17‐propionate by methylation of the N,N‐dimethylhydrazone derivative of dihydrotestosterone is described. A variety of “classical” methylation methods failed to produce the desired product in satisfactory yields unless an unacceptably large excess of 14CH3I was employed.
Pentagastrin analogs containing α‐aminooxy acids VI. Synthesis of two pentagastrin analogs 14C‐labelled at the N‐terminal residue
Authors: Baláspiri L. , Kovács L. , Schőn I. , Kisfaludy L. , Kovács K. , Varga L. , Varró V. 
Published: October 2006

AbstractTert.‐Butyloxycarbonyl‐l‐14C‐glycyl‐L‐tryptophyl‐L‐methionyl‐L‐aspartyl‐L‐phenylalaninamide /I/, H‐l‐14C‐glycyl‐L‐tryptophyl‐L‐methionyl‐L‐aspartyl‐L‐phenyl‐ alaninamide /II/ and tert.‐butyloxycarbonyl‐l‐14C‐aminooxyacetyl‐L‐tryptophyl‐L‐methionyl‐L‐aspartyl‐L‐phenyl‐alaninamide /V/ of different specific radioactivities have been synthesized for biological studies.
Preparation of tritium labelled synthanecine a and its bis‐N‐ethylcarbamate
Authors: Mattocks A. Robin 
Published: October 2006

AbstractA procedure is described for incorporating tritium into the 3‐CH2 side chain of synthanecine A, and preparing the carbamate, 2,3‐bis‐N‐ethylcarbamoyloxymethyl‐l‐methyl‐3‐pyrroline, a hepatotoxic pyrrolizidine alkaloid analogue. The pyrrolizidine amino alcohol, retronecine, can be tritium labelled in a similar way.
Synthese d'Analogues Deuteries des (5α) Androstanediol ‐ 3ξ, 17β
Authors: Jacolot F. , Berthou F. , Picart D. , Le Gall J. Y. , Floch H. H. 
Published: October 2006

AbstractSix deuterated androstanediols were synthetised. The position of deuterium atoms on the molecule were checked by mass spectrometry and 1H or 13c nuclear magnetic resonance. The per cent of d0, d1,… dn‐molecules were calculated.The use of such labelled molecules in the fields of isotopic dilution‐mass fragmentography as carriers and/or internal standards is discussed.
The synthesis of alanine multilabeled with stable isotopes
Authors: Dimitrijevich S. D. , Scanlon M. D. , Anbar M. 
Published: October 2006

AbstractThe work presented illustrates a practical sequence requiring relatively simple and inexpensive aoparatus, and using the commercially available isotopic sources, to produce L‐alanine from M+3 (13C2, 15N) to M+12 (13C3, 15N, D4, 18O2).
Synthese de 1‐alpha‐Methadol et 1‐alpha‐Acetylmethadol Trities
Authors: Do‐Cao‐Thang  , Nguyen‐Hoang‐Nam  , Pontikis R. , Pichat L. 
Published: October 2006

Abstractdl‐Methadone was resolved by crystallization of its ammonium d‐ α ‐ bromocamphor‐ π ‐ sulfonate salt to give d‐methadone. The latter in ethyl acetate solution was reduced with tritium gas to 1‐ α ‐methadol 3H in presence of Adams platinum oxide at normal temperature and pressure. Acetylation of 1‐ α ‐carbinol hydrochloride by means of acetyl chloride afforded 1‐ α ‐acetylmethadol 3H, specific activity : 20 Ci/mMole. The positions and extent of tritium labelling were determined by 3H NMR spectroscopy.
Synthesis of 14C‐labeled 7α‐methoxycephalosporin derivative (14C‐cefotetan)
Authors: Tamazawa Kazuharu , Arima Hideki 
Published: October 2006

Abstract[Caboxamido‐14C]Cefotetan, 7α‐[4‐(carbamoyl carboxymethylene)‐1,3‐dithietan‐2‐yl] [14C]carboxamido‐7α‐methoxy‐3‐(1‐methyl‐1H‐tetrazol‐5‐yl)thiomethyl‐y1)thiomethyl‐3‐cephem‐4‐carboxylic acid (IX), a new cephamycin derivative, was synthesized from bromo[1‐14C]acetic acid for metabolic studies. The results of duplicate preparation of 14C‐Cefotetan are described. In the second synthesis, a new improved method was adopted. The overall radiochemical yields were 21.5 % and 26.7 %, at specific activity of 44.5 μCi/mg and 53.3 μCi/mg respectively.
Incorporation of isotopic oxygen into the carbonyl group of esters and amides
Authors: Kuo Lawrence C. , Koch Timothy R. , Makinen Marvin W. 
Published: October 2006

AbstractSyntheses and analyses are described for incorporation of 17O from 17O‐enriched water into the carbonyl oxygen position of the ester and amide bonds in O‐(trans‐pchlorocinnamoyl)‐L‐β‐phenyllactate and N‐(benzoyl)‐glycyl‐L‐phenylalanine.
Partial synthesis of tritium‐labelled gibberellin‐A3
Authors: Lischewski M. , Adam G. , Liebisch H.‐W. , Pleiß U. 
Published: October 2006

AbstractThe epimeric gibberellin‐A3‐7‐aldehydes 1 and 2 were silylated, enolised with KH and labelled with 3H2O to give after desilylation the tritium‐labelled epimeric gibberellin‐A3‐7‐aldehydes 4 and 5. Subsequent acetylation, oxidation and deacetylation afforded [6‐3H] gibberellin‐A3 (6) and [6‐3H]6‐epi‐gibberellin‐A3 (7). Thus, this route provides a convenient method for the preparation of [6‐3H]GA3 of high specific radioactivity.
The preparation of 11C‐labeled caffeine
Authors: Denutte H. R. , Vandewalle T. , Cattoir H. J. , Vandecasteele C. , Jonckheere J. A. , Slegers G. , Gelijkens C. F. , De Leenheer A. P. 
Published: October 2006

AbstractA rapid and mild procedure for the preparation of [N‐7‐methyl‐11C] caffeine is described. Gaseous 11C‐methyl iodide wa led into dimethyl sulphoxide (DMSO), containing theophylline (1,3‐dimethylaxanthine) and sodium hydride. Purification of the reaction product was achieved by High Performance Liquid Chromatogrphy (HPLC).
Synthesis of iodine‐125 labelled aryl and vinyl iodides
Authors: Kabalka George W. , Sastry Kunda A. R. , Muralidhar Kompally 
Published: October 2006

AbstractIodine‐125 labelled vinyl and aryl iodides are formed via the reaction of sodium iodide‐125 with vinyl‐ and arylboronic acids. Good yields of isomerically pure products are obtained.