Search PubMed⌕ Search

Biomedical subjects

M J Lynch

Publications and source records attributed to M J Lynch.

At least 73 records · Page 4Linked to original sources
PubMed1985

Compound odontoma in a dog.

A compound odontoma was diagnosed in the mandible of a 6-month-old dog. Histologically the tumor consisted primarily of mesenchymal tissue resembling dental pulp, odontoblasts, and areas of dentin. Smaller numbers of ameloblasts were associated with minimal enamel production. Odontomas are benign odontogenic tumors which must be differentiated from malignant bone tumors such as ameloblastic odontoma and ameloblastoma.

Animals↗
PubMed1983

Anticoccidial derivatives of 6-azauracil. 5. Potentiation by benzophenone side chains.

Attachment of p-benzophenone side chains at N1 was found to be one of the most effective modifications for enhancing the potency of 6-azauracil against a broad spectrum of coccidia in chickens. Compound 20 was about 1000-fold more potent than 6-azauracil. Structure-activity relationships paralleled those found in a previously reported series of related analogues containing diphenyl sulfide and sulfone side chains. Drug metabolism studies showed the ketones to be reduced rapidly to carbinols, which are the prevalent species in vivo.

Animals↗
PubMed1982

Electron capture gas-liquid chromatographic determination of morantel-related residues in bovine liver.

A gas-liquid chromatographic assay has been developed to determine major residues of morantel in bovine liver, a target tissue, at levels of 0.2-0.8 ppm. The method is based on hydrolysis of the N-methyltetrahydropyrimidine portion of morantel and its metabolites to N-methyl-1,3-propanediamine, and conversion of the diamine to an N,N'-bis-(2-nitro-4-trifluoromethylphenyl) derivative. The addition of an internal standard, N-ethyl-1,3-propanediamine, to the tissue sample circumvents any potential problem that could arise from variable reaction yields, and eliminates the true recovery as a factor affecting the accuracy and precision of the procedure. The concentrations of the derivatives are determined by pulsed electron capture gas-liquid chromatography over a linear dynamic range equivalent to 0.2-0.8 ppm morantel. The method has been evaluated at 0, 0.2, 0.4, and 0.8 ppm levels in fortified bovine liver, and in a withdrawal sample containing physiologically incurred morantel residues. Mean values of 0.22 +/- 0.015, 0.40 +/- 0.033, and 0.79 +/- ppm were found for fortified samples, 0.02 ppm for control liver, and 0.56 +/- 0.050 ppm for the withdrawal sample.

Animals↗
PubMed1982

Identification and confirmation of pyrantel- and morantel-related residues in liver by gas chromatography-mass spectrometry with selected ion monitoring.

A gas chromatographic-mass spectrometric method with selected ion monitoring (GC/MS-SIM) is described for identification of pyrantel- and morantel-related residues in swine and beef liver. Alkaline hydrolysis of tissue liberates and converts pyrantel- and morantel-related residues to 3-(2-thienyl)-acrylic acid (TAA) and 3-(3-methyl-2-thienyl)-acrylic acid (MTAA), respectively. These thienyl acrylic acids are recovered by ion exclusion chromatography and converted to methyl ester derivatives (TAAE and MTAAE) for identification by GC/MS-SIM. When the relative intensities of the molecular ion, the base peak, and a third significant ion of the sample correspond to ion intensities of the preformed or processed standards, the identity of the residue is confirmed. The method was validated by analysis of swine and beef liver samples containing incurred residues of pyrantel and morantel under withdrawal conditions.

Animals↗
PubMed1981

Anticoccidial derivatives of 6-azauracil. 4. A 1000-fold enhancement of potency by phenyl sulfide and phenyl sulfone side chains.

We report further progress in exploiting our earlier discovery that the anticoccidial activity of 6-azauracil increases markedly when appropriately substituted benzyl or phenyl groups are attached at N-1. With guidance from previous structure-activity relationships and a multiple linear regression analysis, 6-azauracils containing phenyl sulfone or phenyl sulfide side chains were prepared. These prevented a broad spectrum of coccidial infections in chickens at minimum inhibitory concentrations by weight in feed as low as 0.25 ppm, a 4000-fold increase in potency over 6-azauracil, and had shorter plasma half-lives than earlier potent analogues. Sulfides were more potent than sulfones, although they were oxidized rapidly to sulfones in vivo.

Animals↗
PubMed1980

Anticoccidial derivatives of 6-azauracil. 3. Synthesis, high activity, and short plasma half-life of 1-phenyl-6-azauracils containing sulfonamide substituents.

A series of 1-phenyl-6-azauracils containing sulfonamide substituents was prepared. In contrast to previous 1-phenyl-6-azauracils, some of these sulfonamides combine high activity against Eimeria tenella infections in chickens with a very rapid rate of clearance from plasma. Most active was 1-[3'-chloro-5'-methyl-4'-(morpholinylsulfonyl)phenyl]-6-azauracil, with a minimum effective concentration in feed of about 10 ppm.

Animals↗
PubMed1980

Characterization of two new facultative methanotrophs.

Two new facultative methane-oxidizing bacteria have been isolated from lake water enrichments. The organisms have been characterized in terms of colony types, growth characteristics, the guanine plus cytosine content of their deoxyribonucleic acid, thin sections, oxidation rates, and carbon assimilation pathways. Methane-grown cells of both organisms contained intracytoplasmic membranes similar to those described as type II in other methanotrophic bacteria. Neither organism had such membranes when grown heterotrophically. Both organisms assimilated methane by way of the isocitrate lyase-negative serine pathway for formaldehyde incorporation. The enzymes of this pathway were high in specific activity in cells grown on methane and were at low levels in cells grown either on heterotrophic substrates or on heterotrophic substrates plus methane. It is proposed that both organisms be classified in the genus Methylobacterium as two new species, Methylobacterium ethanolicum and Methylobacterium hypolimneticum.

Journal Article↗
PubMed1979

Anticoccidial derivatives of 6-azauracil. 2. High potency and long plasma life of N1-phenyl structures.

Attachment of substituted phenyl side chains at N1 of 6-azauracil caused striking increases in plasma life and anticoccidial potency. The increases were related in part to the acidity of the imide hydrogen. Maximum effects were shown by phenyl rings substituted in both meta positions by compact, electron-withdrawing, lipophilic substituents, as in 1-(3',5'-dichlorophenyl)-6-azauracil, which had plasma half-life of 160 h and a potency 250-fold greater than that of 6-azauracil.

Animals↗
PubMed1975

Transformation antigens on stimulated lymphocytes.

Immunologically mediated regulation of lymphoproliferation requires a self-recognition mechanism. This was sought by measuring the ability of blood lymphocytes to recognize transformed, autologous lymphocytes. Human blood lymphocytes incubated with phytohemagglutinin (PHA) for 72 hr, followed by mitomycin C treatment, induced blast transformation of autologous lymphocytes from all 28 healthy adults tested. Blastogenesis was measured by reactor cell incorporation of 3H-thymidine and was greater at 72 than at 144 hr. The role of PHA itself was assessed in several ways. The supernatant of washed, PHA-transformed lymphocytes did not stimulate normal autologous lymphocytes. Lymphocytes incubated with PHA for 1 hr or 72 hr before mitomycin treatment bound equivalent amounts of 131I-PHA; cells treated for 1 hr did not transform and did not stimulate autologous lymphocytes. By contrast, cells incubated for 72 hr did transform and stimulate autologous lymphocytes. Lytic sonication of PHA-transformed lymphocytes abolished their stimulating capability. An identical result was observed in allogeneic mixed lymphocyte reactions after lytic sonication of the stimulating cells. PHA itself maintained its stimulatory capability after sonication. Although N-acetyl-D-galactosamine (NAGAL) competes with PHA for lymphocyte membrane sites, incubation of reactor lymphocytes with NAGAL did not diminish their response to PHA-transformed autologous lymphocytes. These results strongly suggest the presence of autorecognition determinants on membranes of transformed lymphocytes. The relatively rapid reaction to these determinants is consistent with prior in vivo exposure.

Adult↗