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Biomedical subjects

J C Lloyd

Publications and source records attributed to J C Lloyd.

36 records · Page 2Linked to original sources
PubMed1992

A 27-bp deletion from one allele of the type III collagen gene (COL3A1) in a large family with Ehlers-Danlos syndrome type IV.

A large family with Ehlers-Danlos syndrome type IV (EDS IV) has previously been described. Unlike most cases of EDS IV, fibroblasts from affected members secreted near normal amounts of type III collagen. We have localized the mutation in this family to the CB5 peptide of type III collagen, by using both protein and cDNA mapping techniques. Sequence analysis of cDNA revealed a 27-bp deletion within exon 37, a deletion that removed nine amino acids and maintained the Gly-X-Y repeat of the collagen helix. Further sequencing of genomic DNA confirmed its location, and amplification of DNA from family members showed that it was absent in unaffected individuals but present in all the affected individuals tested. This deletion is flanked by two short direct repeats of CTCC; it may have arisen by slipped mispairing, and has subsequently been transmitted to all affected family members.

Alleles↗
PubMed1991

A novel proline-rich protein from wheat.

A cDNA (WPRP1) encoding a wheat proline-rich protein has been isolated and sequenced. The amino acid composition shows 45% proline, with high levels of methionine, lysine and glutamic acid. The derived 378 residue amino acid sequence has a highly repetitive structure which is unlike those of other proline-rich proteins. The WPRP1 cDNA clone was used to determine the copy number and chromosomal location of the WPRP1 gene by restriction fragment length polymorphism analysis of wheat inbred lines. Although WPRP1 is encoded by a single-copy gene it is also a representative of a larger family of related sequences. RNA gel blot analysis showed that expression of WPRP1 is highest in rapidly growing tissue which together with its amino acid composition suggests a structural role for the encoded protein.

Amino Acid Sequence↗
PubMed1991

The chloroplast FBPase gene of wheat: structure and expression of the promoter in photosynthetic and meristematic cells of transgenic tobacco plants.

A gene encoding chloroplast fructose-1,6-bisphosphatase (FBPase) was isolated from a genomic library of wheat DNA. Comparison of the gene sequence obtained with that of a wheat cDNA clone revealed the presence of three introns, each less than 100 bases in length. One of these introns lies in a region that may be involved in the light activation of FBPase catalytic activity. Chimeric gene constructs comprising 1673 bp of the upstream FBPase promoter region in a transcriptional fusion to the beta-glucuronidase (GUS) reporter gene were used to investigate expression in transgenic tobacco plants. Histochemical localization of GUS activity revealed high levels of expression driven by the FBPase promoter sequences in photosynthetically active tissues and, unexpectedly, also in the meristematic regions of shoots, lateral buds and roots. The biological significance of FBPase expression in meristematic regions is not yet clear but this pattern of expression may be explained by the presence in the FBPase promoter of a short DNA sequence motif which is also found in the CaMV 35S viral promoter.

Amino Acid Sequence↗
PubMed1991

Characterisation of a glycine to valine substitution at amino acid position 910 of the triple helical region of type III collagen in a patient with Ehlers-Danlos syndrome type IV.

We have studied a patient with Ehlers-Danlos syndrome type IV. Protein mapping studies of her type III collagen had indicated that cyanogen bromide fragment 9 contained the site of the mutation. Here we describe the mapping of this region for a single base mutation using a chemical modification and cleavage technique. Sequence analysis of cDNA showed a G to T mutation resulting in the substitution of glycine 910 by valine. This was confirmed by allele specific oligonucleotide hybridisation to the proband's genomic DNA.

Alleles↗
PubMed1989

Complete coding sequence of wheat phosphoribulokinase: developmental and light-dependent expression of the mRNA.

We have isolated and sequenced a cDNA clone which contains the entire coding sequence of the precursor to a subunit of wheat phosphoribulokinase (PRKase). (The enzyme is a homodimer). The cDNA contains 1533 bp and has an open reading frame of 1212 nucleotides. This encodes a protein with an amino-terminal transit sequence of 53 amino acids, while the part that forms the mature protein contains 351 amino acids and has a molecular weight of 39,200 daltons. A comparison of the wheat amino acid sequence with that already known for the mature protein of spinach reveals that there are identical residues in 86% of the positions but their transit peptides differ substantially from one another. The mature wheat and spinach proteins are identical in a segment of over 50 amino acids near the amino-terminus which is the region believed to be involved in ATP binding and in regulation by light of the catalytic activity of the enzyme. We further demonstrate that the expression of PRKase mRNA in wheat leaves is regulated in a developmental, tissue-specific and light dependent manner. We also show that the light-induced increase in the steady-state levels of this mRNA is dependent on the developmental stage of the leaf.

Amino Acid Sequence↗
PubMed1988

Chloroplast fructose-1,6-bisphosphatase: the product of a mosaic gene.

We show here that light stimulates the expression of nuclear genes in wheat leaves for chloroplast fructose-1,6-bisphosphatase (FBPase) and describe a sequence of amino acids in this enzyme which may be responsible, via thioredoxin, for the light regulation of its activity. This data results from (a) our isolation and characterization of a cDNA of this enzyme which contains its entire coding sequence, and (b) our use of this cDNA as a probe to detect mRNA levels in wheat plants subjected to different light regimes. The similarity in amino acid sequence of the encoded enzyme from diverse sources suggests that the FBPase genes all had a common origin. However, their control sequences have been adjusted so that they are appropriately expressed and their coding sequences modified so that the enzymic activity of their products are suitably regulated in the particular cellular environment in which they must function. The light-activated regulatory sequences in the gene for the chloroplast protein have probably come together by a shuffling of DNA segments.

Amino Acid Sequence↗
PubMed1987

Regional localization of carbonic anhydrase genes CA1 and CA3 on human chromosome 8.

The human carbonic anhydrase isozymes represent a family of homologous proteins which are important in respiratory function, fluid secretion, and maintenance of cellular acid-base homeostasis. Using somatic cell genetic techniques we have mapped two of the CA genes (CA1 and CA3) to human chromosome 8. In situ hybridization data demonstrates that both CA1 and CA3 map to the same region (q13-q22) of chromosome 8.

Animals↗
PubMed1986

Influence of sexual preference and chronic hepatitis B virus infection on T lymphocyte subsets, natural killer activity, and suppressor cell activity.

To determine whether abnormalities of cell-mediated immunity are associated with chronic hepatitis B virus infection or with homosexuality, we studied 15 homo- and 11 heterosexual men with chronic hepatitis B virus infection, as well as 11 homo- and 16 heterosexual apparently healthy men. T lymphocyte subsets, natural killer activity, and suppressor cell activity were determined. Homosexual men had significantly lower peripheral blood T4/T8 ratios resulting from a significant increase in T8-positive (suppressor/cytotoxic) cells, and they also had lower natural killer activity. These effects of homosexuality were independent of chronic hepatitis B virus infection, which caused no significant changes independent of homosexuality, and they were not caused by infection with human immunodeficiency virus (formerly HTLV-III/LAV). Suppressor cell function was unaltered in this study. We conclude that studies of cellular immunity in hepatitis B virus infection must take male sexual preference into account.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Monoclonal antibodies for purification and assay of IL-2.

Mouse monoclonal antibodies (Mac 002 and Mac 003) raised against recombinant human Interleukin-2 (rec IL-2), were developed for use as assay and purification reagents. In the Immunoradiometric assay, (IRMA), 125I-Mac 002 is used as tracer, with sheep polyclonal anti-rec IL-2 on the solid phase. This reliably measures rec IL-2 in the range 3-1000 ng/ml. The assay measures natural IL-2 with a lower sensitivity. For some samples of IL-2, the amount detected by IRMA is greater than expected from the biological assays, presumably because there are IL-2 molecules with antigenic, but not biological activity. This is a possible source of variation in the specific activities observed in different preparations of of IL-2. In the purification reagent, Mac 003 is immobilised on sepharose CL-4B to purify recombinant IL-2 from less than 1% in an E. Coli extract, to greater than 90% purity, in a single step with greater than 80% yield.

Animals↗
PubMed1985

Isolation of a cDNA clone for the human muscle specific carbonic anhydrase, CAIII.

The molecular cloning of cDNA for the human muscle specific carbonic anhydrase CAIII is described. The recombinant was isolated from a human muscle cDNA library prepared in the expression vector lambda gt11, and was characterized by hybridization selection and immunoprecipitation. A comparison of insert cDNA and mRNA sizes suggests that the cDNA is full length and includes extensive untranslated sequences. Preliminary sequence data have confirmed the authenticity of this clone and Southern blotting of human and rodent DNA indicates that it will be a useful probe in the analysis of somatic cell hybrids.

Animals↗
PubMed1985

Human glyceraldehyde-3-phosphate dehydrogenase: mRNA levels and enzyme activity in developing muscle.

Analysis of human glyceraldehyde-3-phosphate dehydrogenase mRNA revealed that levels in adult skeletal muscle are 12-fold greater per microgram of polyadenylated RNA than in fetal skeletal muscle, whereas in cardiac muscle RNA levels were about equal in fetal and adult tissue. The mRNA levels correlate well with glyceraldehyde 3-phosphate dehydrogenase enzyme activities. There was no evidence for fetus- or tissue-specific forms.

Adult↗
PubMed1979

Fine-needle aspiration biopsy in ampullary and pancreatic carcinoma.

Cytological verification of the angiographic, sonographic, and/or intraoperative diagnosis of pancreatic or ampullary carcinoma may be achieved by fine-needle aspiration biopsy (FNAB). Fifteen biopsies were done in 13 patients, 12 of whom were thought to have pancreatic carcinoma clinically. The FNAB specimen confirmed this in 11 of them. Also, one equivocal (suspicious), two false-negative, and no false-positive results were recorded. Complications were not seen. In addition, four patients with ampullary carcinoma had pancreatoduodenectomy on the basis of FNAB specimens. Since this method is more accurate and is safer and simpler than the traditional wedge or core biopsy of suspected pancreatic or ampullary tumors, and since it may eliminate the need for laparotomy in selected cases, we consider it the preferred method for immediate diagnosis of these neoplasms.

Adult↗
PubMed1977

Disseminated prothothecosis in a dog.

This is a report on the clinical history and pathological lesions of a dog suffering from disseminated protothecosis due to Prototheca zopfi. Clinically, the dog was presented with bilateral conjunctivitis followed by blindness, deafness and posterior paresis. Pathological lesions were most severe in the eyes and consisted of subacute panophthalmitis with secondary posterior subcapsular cataract, posterior synechia, retinal detachment and microscopic evidence of glaucoma. The kidney, liver, brain, spleen and lungs were also affected. This is believed to be the first published account of protothecosis in mammals other than man in Africa. A review of the literature is included.

Animals↗