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Biomedical subjects

R Wang

Publications and source records attributed to R Wang.

At least 721 records · Page 40Linked to original sources
PubMed1984

Rat liver DT-diaphorase: regulation of functional mRNA levels by 3-methylcholanthrene, trans-stilbene oxide, and phenobarbital.

Total liver poly(A+)-RNA isolated from untreated, and 3-methylcholanthrene-, trans-stilbene oxide-, and phenobarbital-treated rats has been translated in the rabbit reticulocyte lysate system in order to determine the effect of these xenobiotics on the level of translationally active DT-diaphorase mRNA. The in vitro translation systems were subjected to immunoprecipitation with rabbit IgG raised against purified DT-diaphorase and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The identity of the radiolabeled, immunoprecipitated product as DT-diaphorase was confirmed by limited peptide mapping using Staphylococcus aureus V-8 protease. These quantitation results demonstrate that 3-methylcholanthrene leads to an eight-fold elevation in functional DT-diaphorase mRNA at 8 h after a single administration of 3-methylcholanthrene; whereas, trans-stilbene oxide and phenobarbital produced only a modest elevation, two- to three-fold, in the functional DT-diaphorase mRNA level. These data indicate that the increase in the level of DT-diaphorase after 3-methylcholanthrene administration noted previously [B. Höjeberg, K. Blomberg, S. Stenberg, and C. Lind (1981) Arch. Biochem. Biophys. 207, 205-216] can be totally accounted for by an elevation in the mRNA level specific for this protein.

Animals↗
PubMed1984

Drug residue formation from ronidazole, a 5-nitroimidazole. VII. Comparison of protein-bound products formed in vitro and in vivo.

In vivo experiments were conducted with ronidazole radiolabelled in the 2-14CH2-, 4,5-14C-, N-14CH3- and 4-3H-positions. The hepatic protein-bound residues, assessed by the radioactivity of exhaustively washed protein samples, were independent of the radiolabel position and occurred with 4-3H loss (greater than 80%) in excellent agreement to previous results obtained in vitro with anaerobic incubations of liver microsomes (Miwa et al., Chem. Biol. Interact., 41 (1982) 297). HPLC analysis of acid hydrolyzed in vivo protein-bound residues, obtained from [2-14CH2] ronidazole, produced a radiochromatographic profile which was virtually identical to that obtained from a similarly treated in vitro sample. Moreover, almost quantitative (76-96%) liberation of radiolabelled methylamine was obtained from hydrolysates of in vivo and in vitro residue samples formed from [N-14CH3] ronidazole. With 4,5-ring labeled ronidazole the distribution of total radioactivity of the protein hydrolysate on cation exchange resin and the fraction of the residue recovered as oxalic acid were nearly identical for the in vivo and in vitro products. We interpret these data to indicate that ronidazole alkylates proteins with retention of most of the carbon framework of the molecule, in vivo. It is also concluded that the in vitro model, previously used to examine the mechanism of protein alkylation, accurately reflects the salient process initially occurring in the intact animal during the formation of protein-bound residues of this drug.

Alkylation↗
PubMed1984

Bilateral congenital middle ear cholesteatomas.

Congenital middle ear cholesteatomas remain of interest because of their relative rarity and unknown origin. A 4-month-old child presenting with bilateral congenital middle ear cholesteatomas forms the basis for this report. The nature of the epithelial debris found suggests an external origin. An extended transcanal tympanotomy approach for removal, based upon an operative experience of 11 similar ears, will be discussed.

Child, Preschool↗
PubMed1983

Novel applications of monoclonal antibodies.

The ability to "engineer" antibodies, using the techniques of somatic cell genetics and cell fusion, has opened a new era in immunochemistry. No longer are immunologists, limited by the vagaries of polyclonal antibody production. Using hybridoma technology, consistent preparations of precisely defined monoclonal antibodies are now available. Immunochemists are free to pick and choose those precisely defined characteristics of a homogeneous species of antibody that are best suited for a given application. To date, monoclonal antibodies have been used primarily as research chemicals. However, the implications of this new technology for diagnostic, therapeutic, and separation systems are rapidly becoming apparent.

Acid Phosphatase↗
PubMed1983

Coordinate induction of multiple mRNAs specific for rat liver phenobarbital-inducible cytochromes P-450.

Utilizing two-dimensional gel electrophoresis, the polypeptide composition of a purified microsomal cytochrome P-450 preparation isolated from phenobarbital-treated Long-Evans rats obtained from Charles River Laboratories has been examined. The purified protein consists of three polypeptides with nearly identical subunit molecular weights (approximately 52,000) but differing in net charge. These three polypeptides can be detected in liver microsomes isolated from phenobarbital-treated rats by immunoblot analysis but are virtually absent in microsomes isolated from untreated rats. All three polypeptides appear to be products of distinct mRNAs since they can be immunoprecipitated from rabbit reticulocyte lysates programmed with poly(A+)-RNA isolated from phenobarbital-treated rats. The amount of functional mRNA specific for the P-450 polypeptides increases dramatically in response to an acute administration of phenobarbital; however, in untreated rats the amount of functional mRNA was below the level of detection by the translational assay. These data are consistent with the very low level of the phenobarbital-inducible cytochromes P-450 in liver microsomes isolated from untreated rats. Finally, the data indicate that all three cytochrome P-450 mRNAs increase rapidly in response to phenobarbital administration and are regulated coordinately.

Animals↗
PubMed1983

Senile dementia and hydrocephalus due to carotid dolichoectasia.

A 65-year-old hypertensive man presented with progressive dementia, and bilateral lower limb weakness. Computerised tomography revealed carotid arterial dolichoectasia and hydrocephalus. This uncommon entity may constitute another form of surgically treatable dementia in the elderly.

Aged↗
PubMed1981

The hybridoma-an immunochemical laser.

The advent of hybridoma technology has provided the immunotechnologist a finely tunable instrument that should permit a marked advance in the immunologic sciences. The ability to choose the precise antibody required and the virtually unlimited availability of easily purified antibodies have already resulted in the simultaneous immunometric assay and potential reagents for immunoscintigraphy and immunotherapy. Using an antibody with a specific affinity and recognition for a specific antigenc determinant can greatly influence the shape and range of a radioimmunometric calibration curve. With monoclonal antibodies, assay systems based on immune complexes (e.g., turbidimetric assays and counterimmunoelectrophoresis) can be made more precise, thus permitting study of the basic physicochemical principles underlying the antigen-antibody reaction and the development of greatly improved quantitative assays. On the other hand, the ability to select an antibody exhibiting specific characteristics implies the necessity to select. One no longer has the luxury of using a mixture of antibodies, hoping to take advantage of the fact that some will have desirable secondary characteristics such as electrophoretic mobility or the ability to absorb to plastics.

Animals↗
PubMed1981

Monoclonal antibodies in clinical immunology.

Advances in clinical immunodiagnostics resulting from the application of hybridoma technology are starting to appear. Monoclonal antibodies are beginning to displace their antiquated progenitors, polyclonal antisera, in many facets of immunology. Their homogeneity, specificity, and availability make hybridoma-derived antibodies the immunological reagents of the future in immunoassays, immuno-affinity chromatography, immunotherapy, and areas yet to be defined.

Antibodies, Monoclonal↗
PubMed1980

A simplified solid-phase immunofluorescence assay for measurement of serum immunoglobulins.

A simple 2-step solid-phase fluoroimmunoassay for the determination of serum immunoglobulins is described. The method employs a stabilized solid-phase immunoadsorbent consisting of antigen immobilized on a cellulose acetate/nitrate disc attached to a plastic StiQTM sampler. The polymeric disc serves both as a substrate for immobilization and as a highly uniform surface upon which very precise fluorescence determinations may be made. The assays rely upon the reaction of a precise and limiting amount of mono-specific fluorescent antibody with the specific antigen present in a test sample. Residual unreacted fluorescently labeled antibody is allowed to bind to the immunoadsorbent; non-specifically bound antibody is removed in a wash step. The amount of labeled antibody bound is inversely proportional to the amount of antigen present in the test sample. The fluorescence of the bound labeled antibody is measured using a FIAX surface-reading fluorometer. Comparison of this new procedure with the commercially available (4-step) FIAX assay, which requires generation of immunoadsorbent in situ, demonstrated excellent correlation between the two methods. The new 2-step procedure provides results in a much shorter period of time and requires one-half to one-eighth of the operator time required for the other available solid-phase fluoroimmunoassays.

Fluorescent Antibody Technique↗
PubMed1980

Suppression of long-standing incessant ventricular tachycardia by amiodarone.

A 25 year old man had experienced virtually incessant ventricular tachycardia since the age of 16 years, and complained of increasing lethargy and shortness of breath over the past 5 years. Despite medical therapy with numerous conventional antiarrhythmic agents, no single drug or combination of drugs had successfully controlled the tachycardia. Isotope and contrast angiography revealed an enlarged left ventricle with poor function. Electrophysiological studies demonstrate earliest endocardial activation at the left ventricular apex. No electrical procedure terminated tachycardia. Following institution of amiodarone, continuous ECG monitoring revealed periods of sinus rhythm alternating with periods of ventricular bigeminy. Repeat isotope angiography indicated a considerable improvement in L.V. function. There was a corresponding reduction in heart size on the chest radiograph. Clinical improvement was evidenced by disappearance of lethargy and shortness of breath. This report demonstrates that amiodarone, a new antiarrhythmic agent, may suppress long standing incessant ventricular tachycardia resistant to other antiarrhythmic agents. The marked reduction in heart size on amiodarone may suggest that the associated cardiomegaly is secondary to tachycardia.

Adult↗
PubMed1980

Treatment of chronic atrial fibrillation in the elderly, assessed by ambulatory electrocardiographic monitoring.

This study concerns 8 elderly patients with age-related chronic atrial fibrillation that required control of the ventricular response. The effects of oral administration of placebo, pindolol, verapamil, digoxin and digoxin + pindolol were assessed (each for a week) during three daily activity and sleep sessions, over a six-week period. Cardiac rhythm was monitored by taped electrocardiograms. Either digoxin or pindolol was effective, but digoxin was the best tolerated of all the drugs. A combination of pindolol and digoxin reduced the maximum ventricular rate without further depression of the minimum ventricular rate. Digoxin seems to be well tolerated in the control of atrial fibrillation in the elderly, and beta blockade may be a useful therapeutic adjunct.

Aged↗