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Biomedical subjects

A R Brown

Publications and source records attributed to A R Brown.

At least 73 records · Page 4Linked to original sources
PubMed1986

Development of a protocol for newborn screening for disorders of the galactose metabolic pathway.

The protocol evaluated in this paper employs an enzymatic assay of galactose metabolites, thin layer chromatography, and an assay of galactose-1-phosphate uridyl transferase on a single sample of blood collected routinely for newborn screening. Its effectiveness was tested by a retrospective study of known galactosemic blood samples, and also by a prospective study of 207,000 newborn samples from which 6 infants with severe transferase deficient galactosaemia and 2 infants with red cell epimerase deficiency were identified. The detection rate for severe transferase deficiency in the newborn population was 1:35,000. Advantages include low false positive rate, definitive diagnosis within 6 hours of sample receipt, and the use of technically simple and robust procedures. This protocol overcomes the difficulties encountered with previously described procedures.

Australia↗
PubMed1986

Complete nucleotide sequence of an EcoRI-1.35-kb repeated element of mouse: homology with the cellular flanking region between two intracisternal A-particle genes.

The complete DNA sequence (1369 bp) of an EcoRI-1.35-kb repeated element (ER-1) of the mouse BamHI family has been determined. Analysis of this sequence revealed that a portion of the 3' end (positions 1277-1369) of ER-1 was found to share 91% homology with the flanking cellular sequence between two adjacent intracisternal A-particle (IAP) genes, IAP-19A and IAP-19B.

Animals↗
PubMed1985

Nucleotide sequences of murine intracisternal A-particle gene LTRs have extensive variability within the R region.

Nucleotide sequences of the long terminal repeats (LTRs) of four murine intracisternal A-particle (IAP) genes IAP62, 19, 81 and 14 were determined. Each IAP LTR contains three sequence domains, 5'-U3-R-U5-3', and each is bound by 4 bp imperfect inverted repeats. The transcriptional regulatory sequences, CAAT and TATA, as well as the enhancer core sequence GTGGTAA are conserved and precisely positioned within the U3 region. In the R region, the sequence AATAAA is located twenty base pairs preceding the dinucleotide CA, the polyadenylation site. In IAP19 and IAP81, the 5' and 3' LTRs are flanked by a six nucleotide direct repeat of cellular sequences representing the possible integration sites for these IAP proviruses. Both the size and sequences of different IAP LTRs vary considerably, with the majority of the variation localized within the R regions. The size of R varies from 66 bp in IAP14 to 222 bp in IAP62; in contrast, the U3 and U5 regions are all similar in size. These extra sequences within the R region of large LTRs consist of several unusual directly repeating sequences which account for this variability.

Animals↗
PubMed1984

BALB/c antiarsonate idiotypes: gene complementation necessary for expression.

The expression of two idiotype (id) families (5AF6 and 3C6) associated with the BALB/c p-azophenylarsonate-specific antibody response was examined in 11 mouse strains. Eight strains produced some of one or the other of these two id families with the mean percent expression in the anti-Ar responses of id(+) strains ranging from 8 to 43% for the 5AF6 and from 2 to 10% for the 3C6 idiotype. Four strains of mice (C58, AKR, PL, and RF) thought to have Lyt-3.1-linked VL repertoire differences from other mouse strains (Lyt-3.2) were tested for their capacity to contribute to 5AF6 and 3C6 id expression. The RF strain was capable of producing 5AF6 id and small amounts of 3C6 id. Tests of Lyt-3.1 congenic strains C.AKR (AKR Lyt-3.1 on a BALB/c background) and C.C58 (C58 Lyt-3.1 on a BALB/c background) showed that C.AKR could produce 5AF6 id while C.C58 could not. 3C6 id expression was present but depressed in C.C58 mice compared with the high 3C6 id expression in C.AKR. Breeding studies mating C.C58 (bearing the required Igh-Ca-linked VH genes) to other 5AF6(-) strains showed that gene complementation could result in 5AF6 expression in F1 offspring. 5AF6(-) strains capable of complementation included CBA/J, C57BL/6J, AKR/J, and PL/J. C58/J (from which C.C58 were derived) was the only tested strain that failed to complement for 5AF6 id expression. Additional matings between C58/J[5AF6(-)] and CBA/J[5AF6(-)] showed F1 offspring could produce 5AF6 id, indicating that C58/J can contribute functional VH genes necessary for 5AF6 id expression. Depressed expression of 5AF6 and 3C6 id was noted in mice where the C58/J-derived Lyt-3.1 genotype was present. The possibility that the depression of 5AF6 and 3C6 id expression derived from C58/J mice was due to regulatory influences rather than a lack of the VL structural genes is discussed.

Animals↗
PubMed1984

Independent regulation of serologically distinct idiotypes in F1 hybrid mice.

We have investigated the regulation of expression of two distinct intrastrain cross-reactive idiotypes, CRIA and CRIC , characteristic of anti-p-azophenylarsonate (anti-Ar) antibodies of the A/J and BALB/c strains, respectively, in (BALB/c X A/J)F1 ( CAF1 ) mice. Such hybrid mice were found to synthesize antibodies with each idiotype when immunized against the Ar hapten group, although the expression of each was significantly reduced as compared with the parental strain. CAF1 mice were pretreated with idiotypic-specific antibody reagents and subsequently hyperimmunized against the Ar hapten. Analysis of the idiotypes present in immune sera showed that suppression of either CRI did not concomitantly suppress the expression of the other. Alteration of the expression of one idiotype was not, however, without influence on the other; the expression of CRIC was markedly enhanced in mice suppressed for CRIA.

Animals↗
PubMed1984

Idiotypic relationships among anti-p-azophenylarsonate antibodies: shared public idiotopes among A-strain minor CRI and BALB/c CRIc.

Four monoclonal antibodies, each previously categorized as a member of the minor cross-reactive idiotypes of the A/J anti-p-azophenylarsonate (Ar) response, have been subjected to a detailed study of their idiotopes. All four were found to share at least one common public idiotope, with other public idiotopes expressed on some and not others of these antibodies. These CRIm were compared with 7 monoclonal anti-Ar derived from BALB/c mice that have been previously found to bear idiotopes of the BALB/c CRIc. Considerable homology of public idiotopes was demonstrated between the 4 A/J CRIm and 5 of the BALB/c CRIc(+) anti-Ar referred to as the 5AF6 family. The implications of these findings with respect to the structural basis and regulation of these idiotypes are discussed.

Animals↗
PubMed1984

Expression and regulation of two idiotype families and subsets within an idiotype family among BALB/c antibodies against p-azophenylarsonate.

The expression and regulation of the two different idiotype (id) families associated with the anti-p-azophenylarsonate (Ar) antibodies of BALB/c mice were examined. Both families ( 5AF6 and 3C6 ) represented cross-reactive idiotypes (CRI) expressed in the anti-Ar of most individual BALB/c mice. In response to keyhole limpet hemocyanin-Ar, an average of about 28% of BALB/c anti-Ar had 5AF6 family idiotopes, while 3C6 family was expressed on about 16% of BALB/c anti-Ar antibodies. Suppression induced by anti-idiotype treatment against one family did not suppress the expression of the other family, suggesting that the two families were regulated independently. However, the relative expression of one family could influence the expression of the other, because depression of the 5AF6 family tended to increase the expression of the 3C6 family of anti-Ar. Analysis of the 5AF6 family showed that a majority of BALB/c mice produced antibodies bearing most or all of the idiotopes associated with the family, but that a subset of about 35% of the antibodies synthesized lacked idiotopes associated with a monoclonal anti-Ar member of this family, 2.4. Treatment of mice with anti-idiotypes prepared against two different monoclonal anti-Ar of the 5AF6 family produced different effects: one enhanced while the other suppressed idiotype expression, suggesting that there are differences in the idiotopes associated with these two regulatory pathways. Additionally, results indicated that subsets of antibodies within the 5AF6 idiotype family could be regulated independently of each other.

Animals↗
PubMed1983

Cystic fibrosis screening by dried blood spot trypsin assay: results in 75,000 newborn infants.

Seventy-five thousand 5-day-old babies were screened for cystic fibrosis by blood spot immunoreactive trypsin (IRT) assay as part of a statewide screening program. IRT was elevated in 433 babies; retesting revealed persistent elevation in 38. Sweat testing confirmed cystic fibrosis in 35 babies and was normal in two babies, whose IRT remained elevated at the time of the test. Sweat testing was refused by one mother. Of the 35 babies with cystic fibrosis, 13 had meconium ileus or an already diagnosed affected sibling, but the diagnosis was unsuspected in 22, although all but four had some symptoms suggestive of cystic fibrosis. Stool trypsin activity at the time of the diagnostic screen was normal in nine and reduced in seven of the babies with cystic fibrosis. One baby did not have elevated IRT, and the cystic fibrosis was missed by the screening test. In a retrospective study of blood spot samples from 36 newborn infants, who were later diagnosed as having cystic fibrosis, all had IRT levels greater than in matched controls. Our study confirms that elevated IRT is characteristic of newborn babies with cystic fibrosis, and shows that this test is very specific and sensitive when used as a newborn screening test.

Australia↗
PubMed1983

Idiotypic heterogeneity of the cross-reactive idiotype associated with the anti-p-azophenylarsonate antibodies of BALB/c mice.

The cross-reactive idiotype (CRI) associated with the BALB/c antibody response against the p-azophenylarsonate (Ar) hapten was studied by analyzing hybridoma anti-Ar derived from BALB/c mice. The BALB/c CRI (CRIc) was previously thought to be a single idiotype as defined by rabbit anti-idiotype. CRIc has been resolved into at least two separate families of anti-Ar antibodies that are unrelated idiotypically to each other. Analysis of the 5AF6 family revealed considerable idiotypic heterogeneity, including a number of public idiotopes that appeared to be primarily associated with combinatorial idiotopes (requiring H + L chains) or L chain-specific idiotopes.

Animals↗
PubMed1981

Role and strain distribution of genes controlling light chains needed for the expression of an intrastrain cross-reactive idiotype.

Several strains of mice were tested for their capacity to provide immunoglobulin L chains required for the expression of the major cross-reactive idiotype (CRIA) associated with p-azophenylarsonate-specific antibodies of strain A mice. To facilitate testing, mice were bred that were homozygous for Igh-Ce and Lyt-2a, 3a, i.e., they possessed genes controlling H chains but not L chains required for expression of the CRIA. Such male mice were mated to females of various strains and their offspring were tested; expression of CRIA indicated the presence in the female parent of genes controlling the appropriate L chains. All females bearing the Lyt-2a, 3b or Lyt-2b, 3b genotype yielded offspring, most of which were CRIA+, whereas all the offspring of females that were Lyt-2a, 3a were CRIA-. The female parents included mice of several strains that are congenic for Lyt-2a, 3a, Lyt-2b, 3b or Lyt-2a, 3b, thus demonstrating very close linkage between the Lyt loci and the expression of CRIA. In addition, doubly congenic strains of mice with the heavy chain allotype of the CRIA+ AL/N strain and the Lyt-2a, 3a genotype on a BALB/c background failed to express CRIA. The data provide further evidence for the similarity of repertoires of L chains in Lyt-3b mice of various strains. When genes were present controlling A/J H chains and L chains of C57BL/6 or BALB/c origin, the quantitative expression of CRIA was only slightly lower than that observed in A/J mice. Mice possessing genes controlling the H or L chains required for CRIA expression, but not both, did not express CRIA but synthesized Ar-specific antibodies which contained low but significant concentrations of the idiotype-associated chain.

Animals↗
PubMed1981

An intrastrain cross-reactive idiotype associated with anti-p-azophenylarsonate antibodies of BALB/c mice.

This paper describes an intrastrain cross-reactive idiotype, associated with the anti-Ar antibodies of all BALB/c mice tested. The idiotype is present on 20 to 65% of the anti-Ar antibodies of individual BALB/c mice and is localized to the Fab fragment. Adsorption of anti-Ar antibody from an immune serum completely removes the idiotypic activity. Inheritance of the idiotype is linked to the Igh locus, as shown by results obtained with congenic mice. It is present in strains that are Igh-Ia but not in the allotypically related Igh-Ij strains. The idiotype is also present in certain strains belonging to other allotype linkage groups. Expression of the idiotype is suppressed by the administration of rabbit antiidiotypic antibodies before immunization. The BALB/c idiotype is cross-reactive with an idiotype present in a small proportion of anti-Ar antibodies of A/J mice.

Adsorption↗
PubMed1981

Relationship of idiotypes of the anti-p-azophenylarsonate antibodies of A/J and BALB/c mice.

It has previously been shown that A/J anti-Ar antibodies contain 2 different families of cross-reactive idiotypes, referred to as the major and minor idiotypes populations. The present report shows that the minor A/J idiotype is related to a major idiotype of BALB/c anti-Ar antibodies. Anti-idiotype directed against the minor A/J idiotype binds 5 to 10% of A/J anti-Ar but an average of about 40% of BALB/c anti-Ar. This BALB/c population corresponds to the major BALB/c anti-Ar idiotype. For individual BALB/c anti-Ar preparations the maximum percentages of antibody bound by anti-id directed to A/J or BALB/c anti-Ar are very similar. Anti-id reactive with the minor A/J idiotypic population suppressed the formation of the BALB/c major idiotype when injected into BALB/c mice. Adsorption experiments showed that only about one-third of the minor A/J population is related to the BALB/c idiotype and that the expression of this idiotype is highly variable in individual A/J sera. Several types of evidence, obtained with hybridoma products expressing the major A/J idiotype, revealed no detectable relationship between the major A/J and BALB/c anti-Ar idiotypes.

Animals↗
PubMed1981

Properties of a minor cross-reactive idiotype associated with anti-p-azophenylarsonate antibodies of A/J mice.

Experiments are described that further characterize an A/J anti-phenylarsonate (anti-Ar) antibody population, which is idiotypically cross-reactive within the strain but differs from the family of antibodies expressing the major cross-reactive idiotype (CRI). This population has been designated as expressing a "minor" cross-reactive idiotype. Chain recombination studies with hybridoma products (HP) revealed that 2 of 3 HP expressing minor idiotypic determinants contain L chains that are idiotypically closely related to L chains in anti-Ar antibodies bearing the major CRI. The results indicate the expression of the same or very similar L chains in antibodies that differ in idiotype. The minor idiotypic population in serum was investigated by separating antibodies with minor and major idiotypic determinants by use of an immunoadsorbent containing anti-idiotype directed to an HP expressing the major CRI. Studies with the nonadherent, minor idiotypic population showed that such molecules constitute about 8 to 10% of the anti-Ar antibodies in a pool of serum but that individual sera vary markedly in their content of anti-Ar antibodies bearing minor idiotypes. Preinoculation of mice with conventional anti-idiotypic antiserum before immunization with KLH-Ar was found to suppress the appearance of the minor idiotypes as well as the major CRI upon subsequent immunization. The suppression of the minor idiotypic population is presumably mediated by the small fraction of rabbit anti-id antibodies directed against such molecules.

Animals↗
PubMed1980

Quantitation of the anticonvulsant cinromide (3-bromo-N-ethylcinnamamide) and its major plasma metabolites by thin-layer chromatography.

A quantitative thin-layer chromatography (TLC) procedure is described for the analysis of cinromide (3-bromo-N-ethylcinnamamide) and its two major metabolites, 3-bromocinnamamide and 3-bromocinnamic acid in plasma of the dog. These compounds were recovered from acidified plasma by extraction into benzene with a recovery of 95 +/- 5%. All three compounds were quantitated directly on a TLC plate by ultraviolet absorbance densitometry at 270 nm. The linear dynamic range for the quantitation of the compounds on a TLC plate ranged between 10 and 1000 ng. The complete procedure is useful in the working range of 50 ng/ml to 100 microgram/ml of plasma with a coefficient of variability of about 10%. Specificity of the method for parent drug and each of its plasma metabolites was confirmed by high-performance liquid chromatography. The method was used to determine the pharmacokinetics of cinromide and its two major plasma metabolites in dogs following a single oral dose of the drug.

Animals↗