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Biomedical subjects

G Allen

Publications and source records attributed to G Allen.

At least 127 records · Page 7Linked to original sources
PubMed1987

The non-decline in U.S. twin birth rates, 1964-1983.

Detailed twin birth rates for the United States are unavailable since 1964. In 1983 the crude twinning rate for women of white race was higher than in 1964, but there had been great changes in maternal age and parity. Indirect standardization for maternal age and birth order provides estimated total twinning rates that can be compared over the entire period. The adjusted rates for whites show a nearly continuous increase except after a 2-year reporting hiatus, 1969-70, when rates dropped back 10%. In blacks the adjusted rate increased between 1966 and 1978, except for the 1968-71 shift. The distributions of rate increases by maternal age and by race argue against effects of medical ovulation stimulants, but a disproportionate increase of triplets argues for such effects. Study is needed of rates specific for maternal age and parity, rather than of total rates.

Birth Rate↗
PubMed1987

The monozygotic twinning rate: is it really constant?

Weinberg's difference method, applied to twin birth statistics, usually shows a dependence of the MZ rate on maternal age, like a thin shadow of the DZ rate. Some of this MZ variation could be explained away by James' finding of more same-sex (SS) than opposite-sex (OS) DZ twins, the excess being mistakenly classified as MZ by Weinberg's assumption of equal numbers. By several methods one can extract a constant value for the MZ rate and a constant or nearly constant value for the DZ SS/OS ratio, but these "constants" are actually arbitrary and they vary between populations.

Birth Order↗
PubMed1986

Bacterially expressed antigenic peptide from foot-and-mouth disease virus capsid elicits variable immunologic responses in animals.

A fusion protein consisting of beta-galactosidase (GZ) to which was attached at its N-terminus the amino acid sequence corresponding to residues 142-160 of the immunogenic protein VP1 of foot-and-mouth disease virus (FMDV) has been expressed in E. coli. A chemically synthesized section of DNA corresponding to the amino acid sequence 142-160 was inserted into a vector (pXY410) designed to express fusion proteins with the carboxy terminal 1015 amino acids of GZ. The hybrid protein immunopurified by a GZ-specific monoclonal antibody was soluble, retained full GZ activity, and induced virus-neutralizing antibody in guinea pigs and mice. There were significant differences between the responses of individual mice to the FMDV peptide sequence, although the titers against GZ were uniformly high. This variable pattern did not change after hyperimmunization and was demonstrable in a range of mouse strains of different haplotype. The same results were obtained whether the response was measured by virus neutralization or by RIA against the FMDV peptide sequence. The possible reasons for the variable recognition of the FMDV epitopes by individual mice are discussed.

Animals↗
PubMed1986

Cloning, nucleotide sequencing, and expression of tetanus toxin fragment C in Escherichia coli.

The amino acid sequence of the first 30 residues of fragment C of tetanus toxin was determined, and a mixture of 32 complementary oligonucleotides, each 17 bases long, was synthesized. A 2-kilobase (kb) EcoI fragment of Clostridium tetani DNA was identified by Southern blotting and was cloned into the Escherichia coli plasmid vector pAT153 with the 32P-labeled oligonucleotide mixture as a probe. A second 3.2-kb Bg/II fragment was identified and cloned with the 2-kb EcoRI fragment as a probe. The nucleotide sequence of 1.8 kb of this DNA was determined and was shown to encode the entire fragment C and a portion of fragment B of tetanus toxin. The tetanus DNA was expressed in E. coli with pWRL507, a plasmid vector containing the trp promoter and a portion of the trpE gene. The trpE-tetanus fusion proteins were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and were shown to react with anti-fragment C antibody.

Base Sequence↗
PubMed1985

Zygosity partitioning of small twin samples.

When the Weinberg estimate of the proportion of monozygotic pairs is quite deviant from that in the source population, it is likely to be wrong because Weinberg's difference is much less stable than the zygosity proportions. A formula is proposed for the probability distribution of possible compositions of a small sample of twins based on sex concordance in the sample and zygosity proportions in the source population.

Female↗
PubMed1985

Production of epidermal growth factor in Escherichia coli from a synthetic gene.

Mouse epidermal growth factor (EGF) is under investigation as a deflecting agent for sheep. Substantial quantities of the pure protein are required for these studies and to supply this need a gene for the protein was synthesized and inserted into plasmid vectors to direct the expression of EGF polypeptide, or fusion proteins containing the EGF peptide sequence, in transformed Escherichia coli. Mature EGF was released by lysine specific proteolysis of a fusion protein consisting of part of the E. coli TrpE protein, a lysine linker and EGF polypeptide. The EGF was purified and characterized and was found to be biologically active.

Base Sequence↗
PubMed1984

Clinical utility of the relationship between fetal femur length and biparietal diameter.

The relationship between fetal femur length and biparietal diameter on ultrasound examination was evaluated in a large, unselected obstetric population of 12-40 weeks' gestational age. The derived ratio of fetal femur length to biparietal diameter was evaluated retrospectively as a tool for examining the technical reliability of fetal measurements obtained and as a screening mechanism for detecting asymmetric fetal development. The ratio of femur length to biparietal diameter is of value as an aid to the detection of fetal developmental anomalies and should be a routine parameter considered in the performance of an obstetric ultrasound examination.

Birth Weight↗
PubMed1983

Locations of the six disulphide bonds in a variant surface glycoprotein (VSG 117) from Trypanosoma brucei.

The locations of the six disulphide bonds and the single free cysteine residue in a variant surface glycoprotein, VSG 117, from the African trypanosome Trypanosoma brucei have been determined to be Cys-14--Cys-140, Cys-121--Cys-182, Cys-389--Cys-404, Cys-398--417, Cys-447--Cys-461 and Cys-455--Cys-468. Cys-244 bears the single thiol group, which is unreactive towards 2-nitro-5-thiocyanobenzoate in the native molecule and is probably buried. Biosynthetically incorporated [35S]cysteine aided the location of the disulphide bonds. Two proteinase-resistant glycosylated domains, each containing two disulphide bonds, were identified in the C-terminal region of the glycoprotein. Details of purification of [35S]cysteine-containing peptides, and Tables of amino acid analyses, are presented in Supplementary Publication SUP 50119 (32 pages), which has been deposited with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1981) 193,5.

Animals↗
PubMed1982

Structure and properties of human interferon-alpha from Namalwa lymphoblastoid cells.

The chromatographic properties of human interferon-alpha from Namalwa lymphoblastoid cells on Sephadex G-75 are described. The interferons are separated into two groups of four, with apparent molecular weights 19050 and 22000. Some of the latter form dimers at high concentrations. Fractions containing interferon were studied by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. Seven of the components had apparent molecular weights in this system, after reduction, of between 18400 and 20900: one component is probably glycosylated and has an apparent molecular weight of 27500. Amino acid sequences of peptides derived from interferon mixtures were determined and are related to published sequences deduced from the nucleotide sequences of cloned complementary DNA coding for interferon-alpha. The results show that the major interferon-alpha species isolated from Namalwa cells do not undergo C-terminal processing. Amino acid analyses of peptides are presented in Supplementary Publication SUP 50117 (28 pages), which has been deposited with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1981) 193, 5.

Amino Acid Sequence↗