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Biomedical subjects

B S McGuire

Publications and source records attributed to B S McGuire.

At least 19 recordsLinked to original sources
PubMed1997

Phenytoin-induced depletion of folate in rats originates in liver and involves a mechanism that does not discriminate folate form.

The anticonvulsant phenytoin causes a decrease in plasma concentrations of folate in epileptic patients. The mechanism underlying this depletion is unknown. To study this mechanism, phenytoin was administered to rats by addition to the diet (3 g phenytoin/kg diet) for up to 8 wk. At selected times during phenytoin administration (0, 3, 7, 10, 14, 28, 42 and 56 d), the composition of the folate pools of intestinal mucosa, liver, bile and brain was determined. The 0-d administration served as the control group. The controls were fed the same diet without phenytoin for the eight weeks of the experiment. Phenytoin administration had minimal effect on either the folate concentration or the composition of the folate pool in intestinal mucosa. Phenytoin administration did, however, cause a depletion of total hepatic folate to about 50% of control, causing the pentaglutamate derivatives of each of the pteridine derivatives to decline rapidly, with the formyl and dihydro derivatives of the pteridine moiety falling more rapidly than the methyl and methylene + tetrahydro derivatives. The monoglutamate of the methylene + unsubstituted tetrahydro derivative increased significantly with time of phenytoin treatment. The mono- and di-glutamate derivatives of the methyltetrahydrofolate increased transiently and significantly in the bile, and the polyglutamate chain length increased significantly in the brain with time of phenytoin treatment. We conclude that phenytoin inhibits the formation of polyglutamyl folates in rat liver.

Administration, Oral↗
PubMed1996

Formyltetrahydrofolates associated with mitochondria have longer polyglutamate chains than the methyltetrahydrofolates associated with cytoplasm in rat brain.

The subcellular distribution of folate coenzymes in the brain is unknown. Brain folate concentrations are low and hence require a sensitive assay to determine the subcellular distribution. Rat brain was fractionated by differential centrifugation into cytoplasmic, mitochondrial and crude synaptosomal fractions. The compositions of the folate pools in these subcellular fractions were determined by differential conversion of one-carbon forms enzymatically to 5,10-methylenetetrahydrofolate (5,10CH2H4PteGlu(n)) followed by reaction of the 5,10CH2H4PteGlu(n) with thymidylate synthetase and [3H]fluorodeoxyuridylate to form ternary complexes, which were then separated as a function of polyglutamate chain length by isoelectric focusing, visualized by fluorography and quantified by densitometry. The distribution of the pteridine derivatives in brain was very similar to the distribution of these derivatives in liver. Cytoplasm contained primarily 5-methyltetrahydropteroylpolyglutamates with smaller amounts of unsubstituted tetrahydropteroylpolyglutamates, whereas mitochondria contained approximately equal concentrations of unsubstituted and formyl-substituted tetrahydropteroylpolyglutamates. The subcellular distribution of polyglutamate derivatives in brain, however, was different from that in liver. In the brain, the mitochondrial folates exhibited longer polyglutamate chains than did the cytoplasmic folates, a pattern opposite to that in the liver. Whereas the brain cytoplasmic pteroylpolyglutamates were primarily penta and hexa glutamates, the brain mitochondrial pteroylpolyglutamates were primarily hexa and hepta glutamates. The brain also contained small but measurable levels of oxidized folates, which were seen in crude synaptosomal fractions but not in cytoplasmic or mitochondrial fractions.

Animals↗
PubMed1995

Rat liver subcellular folate distribution shows association of formyltetrahydropteroylpentaglutamates with mitochondria and methyltetrahydropteroylhexaglutamates with cytoplasm.

The ternary complex method for the determination of folylpolyglutamates was combined with procedures for interconverting folate derivatives to measure 28 different folate derivatives in the subcellular fractions of rat liver. Folates in the homogenate showed a typical distribution with nearly equal quantities of penta- and hexaglutamates and pteridine derivatives in decreasing order as follows: 1) methyl substituted folates [5-methyltetrahydropteroylglutamates], 2) unsubstituted folates [tetrahydropteroylglutamates + 5,10- methylenetetrahydropteroylglutamates], 3) formyl substituted folates [5-formyltetrahydropteroylglutamates + 10- formyltetrahydropteroylglutamates + 5,10-methenyltetrahydropteroylglutamates], and 4) oxidized folates [dihydropteroylglutamates]. In the homogenate the methyl substituted folates exhibited a higher hexa:pentaglutamate ratio than did the other pteridine derivatives. As the fractionation proceeded toward purer subcellular components, the methyl substituted folates were found almost exclusively in the soluble fraction, and this fraction also contained the higher hexa:pentaglutamate ratio characteristic of the methyl substituted folates. The plasma membrane, the microsomal and the nuclear fractions did not contain appreciable folate. The mitochondrial fraction contained primarily formyl substituted and unsubstituted folates, and these folates exhibited the lower hexa:pentaglutamate ratios. These data support the hypothesis that folate-dependent one-carbon metabolism is compartmentalized in the eukaryotic cell.

Acid Phosphatase↗
PubMed1995

Natural occurrence and characterization of the Lyme disease spirochete, Borrelia burgdorferi, in cotton rats (Sigmodon hispidus) from Georgia and Florida.

This is the first report of natural infection by Borrelia burgdorferi in the cotton rat Sigmodon hispidus. Nine B. burgdorferi isolates were obtained from ear tissues, urinary bladders, or both, by culturing tissues in BSKII medium. The rat from which the SI-3 isolate was cultured was from the same site (Sapelo Island, Georgia) as an infected cotton mouse Peromyscus gossypinus and Ixodes scapularis tick reported previously. The 8 B. burgdorferi isolates from rats in Florida included 1 (AI-1) from Amelia Island, 1 (FD-1) from Faver-Dykes State Park, and 6 (MI-3 through MI-8) from Merritt Island. The distance between Sapelo Island and Merritt Island is approximately 400 km. All B. burgdorferi isolates were characterized by indirect immunofluorescence using monoclonal antibodies to OspA (H3TS, H5332) and OspB (H5TS, H6831), polymerase chain reaction detection of specific B. burgdorferi B-31 DNA target sequences (ospA, fla, and a random chromosomal sequence), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of spirochetal proteins. The phenotypic and genotypic characteristics of the isolates are discussed, as well as the probable importance of the cotton rat as a reservoir for B. burgdorferi in the southern United States.

Animals↗
PubMed1993

Isolation and transmission of the Lyme disease spirochete from the southeastern United States.

The isolation of the Lyme disease spirochete (Borrelia burgdorferi) from the southeastern United States is reported. Three isolates, two from cotton mice (Peromyscus gossypinus) and one from the black-legged tick (Ixodes scapularis), were recovered from Sapelo Island, Georgia, in July and September 1991. The spirochetes were characterized by indirect fluorescent antibody assay using a battery of five monoclonal antibodies, by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS/PAGE) of whole cell lysates, and by the polymerase chain reaction (PCR) assay using primers for three DNA target sequences found in B. burgdorferi reference strain B-31. Transmission experiments indicate that the three Georgia isolates can infect experimentally inoculated hamsters and mice. Tick transmission of one of the isolates has been attempted so far; I. scapularis transmitted isolate SI-1 from hamsters to mice, but the lone-star tick, Amblyomma americanum, did not.

Animals↗
PubMed1992

Detection of Borrelia burgdorferi in laboratory-reared Ixodes dammini (Acari: Ixodidae) fed on experimentally inoculated white-tailed deer.

Larvae and nymphs of Ixodes dammini Spielman, Piesman, Clifford & Corwin from a laboratory colony were fed on two white-tailed deer, Odocoileus virginianus (Zimmerman) inoculated with either the SH2-82 or JD-1 strains of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner. Ticks were exposed to one deer 43 and 69 d after inoculation of the spirochete and to a second deer 35 and 61 d after inoculation. Polymerase chain reaction assays amplified the 158 bp OspA DNA target sequence in 11.1% (n = 9) of fed larvae and 3.3% (n = 30) of nymphs from the deer inoculated with the SH2-82 strain, and 22.7% (n = 22) of larvae and 0% (n = 21) of nymphs from a second deer inoculated with the JD-1 strain of B. burgdorferi. One of three females derived from nymphs fed on one of the inoculated deer showed presence of B. burgdorferi DNA, but none of four males was positive. Experimentally inoculated deer can serve as a source of at least two geographic strains of B. burgdorferi to I. dammini larvae and nymphs for at least several weeks.

Animals↗
PubMed1992

Detection of Borrelia burgdorferi in human blood and urine using the polymerase chain reaction.

We investigated the use of the polymerase chain reaction (PCR) to detect Borrelia burgdorferi strain B-31 in human blood and urine experimentally inoculated with 5 and 1 borreliae/cm3, respectively, and to biotinylate a DNA probe specific for B. burgdorferi in the dot blot and Southern blot assays. When the blood and urine samples were subjected to PCR, a 370-bp amplified product was consistently visible on agarose gel electrophoresis after 30 and 45 cycles, respectively. The total human genomic DNA extracted from a 1-cm3 sample of inoculated blood was approximately 6.25 micrograms, and the total amount of B. burgdorferi DNA was estimated to be 0.01 pg/6.25 micrograms of the human DNA. For PCR, 2.5 micrograms of human DNA which contained the equivalent of 0.004 pg of borrelia DNA (approximately two borreliae) were used for enzymatic amplification. When 1/20 or 1/10 of the PCR-amplified products were used either for dot blot or Southern blot hybridization, the accessible copies of amplified B. burgdorferi DNA were sufficient for detectable hybridization to occur. PCR amplification of B. burgdorferi DNA in clinical specimens followed by dot blot hybridization may be a valuable adjunct or alternative to current but inadequate laboratory methods for the diagnosis of Lyme disease.

Base Sequence↗
PubMed1991

Chlamydia trachomatis in chronic abacterial prostatitis: demonstration by colorimetric in situ hybridization.

Twenty-three transurethral resected prostate specimens with histologic evidence of chronic abacterial prostatitis were evaluated by colorimetric in situ hybridization for evidence of Chlamydia trachomatis. Intracellular chlamydia bodies were detected in seven of 23 cases (30.4%). In five of seven positive cases, chlamydia inclusion bodies were present within both epithelial cells and intraluminal histiocytes. In two of seven positive cases, extracellular chlamydia bodies were identified in conjunction with intraepithelial inclusions. In only one case were extraductal, extraacinar, intrahistiocytic inclusion bodies observed. Our study confirms previous reports implicating C trachomatis as an etiologic agent in chronic abacterial prostatitis, and underscores the applicability of DNA probes for the detection and identification of C trachomatis in routinely fixed, paraffin-embedded tissues.

Chlamydia Infections↗
PubMed1991

Differential expression of c-myc and H-ras oncogenes in Barrett's epithelium. A study using colorimetric in situ hybridization.

To determine the role of c-myc and H-ras in progressive, dysplastic Barrett's mucosa (BM), and the usefulness of these oncogenes as markers for dysplastic lesions at high risk for malignant transformation, sequential formaldehyde solution-fixed, paraffin-embedded biopsy specimens that were obtained from 12 patients with BM were evaluated by in situ hybridization with the use of biotinylated complimentary DNA probes. Nine of the patients were taken from a previous prospective study. Four of these nine patients had dysplasia, and adenocarcinoma had developed in two of them; five had nondysplastic BM only. Two additional patients had adenocarcinoma, but their initial biopsy specimens had revealed dysplasia. One additional patient had intermediate-grade dysplasia. The intensity of oncogene expression was quantified by computerized color-image analysis. Enhanced c-myc expression of approximately equal intensity was consistently observed in all grades of dysplasia and carcinoma. H-ras was also consistently expressed in higher grades of dysplasia and carcinoma but not in low-grade dysplasia. Neither c-myc nor H-ras expression was detected in nondysplastic BM. The expression of H-ras in dysplastic BM appears to be a helpful marker for identifying which dysplastic lesions will progress to carcinoma.

Chronic Disease↗
PubMed1990

Mitochondrial enzymes responsible for oxidizing medium-chain fatty acids in developing rat skeletal muscle, heart, and liver.

Prior to weaning, medium-chain fatty acids constitute an important energy source in the developing rat. Fatty acid oxidation rates increase with age in most developing tissues, but the pattern of this increase may vary according to the role of the particular organ. In skeletal muscle, heart, and liver of developing rats, we measured mitochondrial activities of long- and short-chain enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and long- and short-chain acyl-CoA thiolase. In skeletal muscle, the pattern of development in fatty acid oxidation enzymes favored utilization of long-chain rather than medium-chain fatty acids. In liver, enzyme activities for medium-chain fatty acids were highest prior to weaning. Heart occupied a position intermediate between skeletal muscle and liver.

Journal Article↗
PubMed1990

Enhanced expression of c-myc and H-ras oncogenes in Letterer-Siwe disease. A sequential study using colorimetric in situ hybridization.

Tissues from two patients with disseminated histiocytosis X (Letterer-Siwe disease) in which histiocytosis X cells exhibited histologic and cytologic features of malignancy were evaluated by in situ hybridization with the use of biotinylated nucleic acid probes to c-myc and H-ras oncogenes. Enhanced expression of these oncogenes was observed in mononucleated and multinucleated cells of histiocytosis X in the terminal proliferative phase but not in the early quiescent phase of Letterer-Siwe disease in both patients. Our findings indicate that deregulation of c-myc and H-ras in histiocytosis X are late events that likely confer a selective growth advantage to histiocytosis X cells.

DNA Probes↗
PubMed1989

Acyl-CoA dehydrogenase enzymes during early postnatal development in the rat.

Fatty acid oxidation rates tend to increase with age in most developing tissues. In skeletal muscle, heart, and liver of developing rats, we measured activities of three acyl-CoA dehydrogenase enzymes, which constitute the first step in the mitochondrial beta-oxidation sequence. In skeletal muscle, activities of all three enzymes increased with age. In heart muscle, palmityl-CoA dehydrogenase increased, while the other two enzymes changed only minimally. In liver, palmityl-CoA dehydrogenase activity steadily increased with age. Decanoyl- and butyryl-CoA dehydrogenase also increased with age, but much more irregularly. We also examined the electrophoretic characteristics of these enzyme proteins in the three tissues. There were no changes in their electrophoretic patterns during development.

Acyl-CoA Dehydrogenase↗
PubMed1986

Fatty acyl-CoA dehydrogenase enzymes in human skeletal muscle.

An electrophoretic and enzyme-substrate staining technique for acyl-CoA dehydrogenase (ACD) enzymes was developed for use with small (less than 100 mg) tissue samples. Based on their electrophoretic mobility and substrate staining specificity, at least two and perhaps three chain-length specific enzymes for dehydrogenation of saturated fatty acids were found in human skeletal muscle. ACD enzymes staining with octanoyl-CoA or palmitoyl-CoA were identified by this technique in human skeletal muscle, heart, and liver, but the ACD enzyme staining with butyryl-CoA was difficult to detect and was definitely visualized only in skeletal muscle.

Acyl-CoA Dehydrogenases↗
PubMed1984

Immunochemical identification of normal and variant hemoglobins after electrophoretic separation and transfer to nitrocellulose membranes.

A highly specific method for the conclusive identification of normal and variant human hemoglobins is described in this communication. The method employs the standard electrophoretic technique in combination with the immunoblot technique using monospecific antisera raised in rabbits. Various hemoglobins such as Hb, S, C, A2, and F were separated on an alkaline polyacrylamide gel or a cellulose-acetate membrane, and transferred to a nitrocellulose membrane and the individual hemoglobins were identified by the immunoblot procedure. With this method hemoglobins with similar or identical electrophoretic mobilities can be definitively identified with the use of monospecific antisera.

Electrophoresis, Cellulose Acetate↗
PubMed1984

Identification and quantification of hemoglobins A2 and Barts with an enzyme-labeled immunosorbent assay.

The presence and quantity of hemoglobins Barts and A2 in hemolysates from normal donors and individuals with alpha- and beta-thalassemia trait, respectively, were determined with an enzyme-labeled immunosorbent assay (ELISA). This technique requires the incorporation of monospecific antisera capable of specifically reacting only with these hemoglobins, e.g., with the delta chain of Hb A2 and gamma 4 chains of Hb Barts. By the ELISA, the mean percentage of Hb Barts in hemolysates from normal persons and persons with alpha-thalassemia was 0.25 (SD 0.07) and 6.1 (SD 0.40), respectively. Corresponding values for Hb A2 in hemolysates from normals and persons with beta-thalassemia were 3.1 (SD 0.22) and 5.9 (SD 0.21), respectively. The results obtained by the ELISA procedure were in good agreement with those determined by radioimmunoassay or microcolumn chromatography. The ELISA technique is more sensitive and specific than biochemical assays currently used to measure these hemoglobins and can detect 250 ng of Hb Barts in 100 micrograms of hemoglobin or 50 ng of Hb A2 in 5 micrograms of hemoglobin.

Adult↗
PubMed1983

The modeled structure of the IgG Gar VL region and its implications for anti-flavin and anti-DNP fine specificities.

The variable domain (V) sequence of the lambda-light chain of the Gar IgG2 human myeloma protein was determined from enzymatically generated peptides that were isolated, characterized, and ordered by overlap and/or by subgroup homology. The sequence consisted of the amino terminal 107 residues of the light chain, and shared subgroup V lambda III-specific residues as well as a pattern of CDR deletions unique to most V lambda III sequences. The structural role of the light V region in the high affinity for flavins and the low affinity for 2,4-dinitrophenyl haptens characteristic of the intact IgG molecule was coarsely assessed by way of model building and by comparison with the refined combining site model of MOPC 315, an Ig with relative affinity values for DNP and riboflavin the converse of those observed in Gar.

Amino Acid Sequence↗
PubMed1980

The V region sequence of lambda Bence-Jones protein Wh: evidence for separate germ-line sets within lambda-subgroups.

The complete variable region sequence of the glycosylated Bence-Jones protein Wh has revealed that the most hypervariable segments of the first and third complementarity-determing regions (CDR) are identical with those of another glycosylated Bence-Jones protein (Nei) of the same lambda-subgroup. The carbohydrate is attached in both proteins at the identical sequences in the third CDR, and the sequences of the first CDR differ at only one position in fourteen. Because CDR sequence comparisons more sensitively reflect overall germ-line V gene similarities, proteins Wh and Nei could possibly reflect a "set" relationship analogous to the mouse V kappa isotype. Cluster analyses of currently available V lambda sequences supported this suggested relationship.

Amino Acid Sequence↗