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Biomedical subjects

I Craig

Publications and source records attributed to I Craig.

At least 19 recordsLinked to original sources
PubMed1992

Long-range chromosomal mapping of the carcinoembryonic antigen (CEA) gene family cluster.

A long-range physical map of the carcinoembryonic antigen (CEA) gene family cluster, which is located on the long arm of chromosome 19, has been constructed. This was achieved by hybridization analysis of large DNA fragments separated by pulse-field gel electrophoresis and of DNA from human/rodent somatic cell hybrids, as well as the assembly of ordered sets of cosmids for this gene region into contigs. The different approaches yielded very similar results and indicate that the entire gene family is contained within a region located at position 19q13.1-q13.2 between the CYP2A and the D19S15/D19S8 markers. The physical linkage of nine genes belonging to the CEA subgroup and their location with respect to the pregnancy-specific glycoprotein (PSG) subgroup genes have been determined, and the latter are located closer to the telomere. From large groups of ordered cosmid clones, the identity of all known CEA subgroup genes has been confirmed either by hybridization using gene-specific probes or by DNA sequencing. These studies have identified a new member of the CEA subgroup (CGM8), which probably represents a pseudogene due to the existence of two stop codons, one in the leader and one in the N-terminal domain exons. The gene order and orientation, which were determined by hybridization with probes from the 5' and 3' regions of the genes, are as follows: cen/3'-CGM7-5'/3'-CGM2-5'/5'-CEA-3'/5'-NCA-3'/5'-CGM1- 3'/3'-BGP-5'/3'- CGM9-5'/3'-CGM6-5'/5'-CGM8-3'/PSGcluster/qter.

Amino Acid Sequence↗
PubMed1992

Effect of vitrectomy and cytopreparatory techniques on cell survival and preservation.

Obtaining vitreous fluid by means of vitrectomy frequently results in a specimen that is difficult to assess cytologically. We devised an experimental model to examine the effect of the vitrector on human leukemic cancer (HL60) cells in suspension and to evaluate the cytopreparatory techniques of membrane filtration and cytocentrifugation. Eighteen 3-mL specimens of cells at concentrations ranging from 1 to 9 x 10(5)/mL were vitrectomized, and eighteen 3-mL control samples matched for cell concentration were obtained atraumatically. No significant difference in cell loss, as determined by means of staining with nigrosin vital dye, was found at any cell concentration between the vitrectomized and control specimens. The specimens were then processed cytologically. On cytologic assessment it was not possible to distinguish the vitrectomized and control specimens. A higher degree of cell preservation was noted at higher cell concentrations regardless of the cytopreparatory technique, but at lower concentrations membrane filtration resulted in a higher proportion of cytologically assessable specimens than did cytocentrifugation (42% vs. 22%). The results suggest that the vitrector causes minimal cellular damage and that to obtain optimal results both cytopreparatory techniques should be used with all vitrectomy specimens.

Cell Count↗
PubMed1991

Structure of the human gene for monoamine oxidase type A.

Monoamine oxidases, type A and type B, are principal enzymes for the degradation of biogenic amines, including catecholamines and serotonin. These isozymes have been implicated in neuropsychiatric disorders. Previously, cDNA clones for both MAO-A and MAO-B have been sequenced and the genes encoding them have been localized to human chromosome Xp11.23-Xp11.4. In this work, we isolated human genomic clones spanning almost all the MAOA gene from cosmid and phage libraries using a cDNA probe for MAO-A. Restriction mapping and sequencing show that the human MAOA gene extends over 70 kb and is composed of 15 exons. The exon structure of human MAOA is similar to that described by others for human MAOB. Exon 12 (bearing the codon for cysteine, which carries the covalently bound FAD cofactor) and exon 13 are highly conserved between human MAOA and MAOB genes (92% at the amino acid level). Earlier work revealed two species of MAO-A mRNA, 2.1 kb and 4.5-5.5 kb. We now report on further cDNA isolation and sequencing, which demonstrates that the longer message has an extension of 2.2 kb in the 3' noncoding region. This extended region is contained entirely within exon 15. The two messages therefore appear to be generated by the use of two alternative polyadenylation sites. Results from the present work should facilitate the mutational analysis of functional domains of MAO-A and MAO-B. Knowledge of the gene structure will also help in evaluating the role of genetic variations in MAO-A in human disease through the use of genomic DNA, which is more accessible than the RNA, as a template for PCR-amplification and sequencing.

Amino Acid Sequence↗
PubMed1991

How common are epileptic seizures in old age?

A large primary-care computerized database was searched to determine the incidence and prevalence of epilepsy and epileptic seizures in old age compared with the general population. The prevalence of subjects with a diagnosis of epileptic seizures was higher in older age groups: 10.9/1000 for sexagenarians, 12.0 for septuagenarians and 13.1 for those over 80, compared with 9.0/1000 in the overall population. The overall prevalence in subjects aged over 60 was 11.8. Annual incidence rose even more sharply in old age: 76/100,000 for sexagenarians, 147 for septuagenarians, and 159 for those over 80, compared with an overall population incidence of 69/100,000. The overall incidence in subjects over 60 was 117. Of incident cases requiring treatment, 35.5% were over 60 years old. Our findings are in keeping with other recent epidemiological studies and in part reflect the age-associated increase in the prevalence of cerebrovascular disease. They have implications for the organization of services for elderly people, for the education of general practitioners and hospital doctors and for directing epilepsy research.

Aged↗
PubMed1991

Carrier detection in X-linked retinitis pigmentosa by multipoint DNA analysis. Problems due to genetic heterogeneity.

DNA diagnosis of X-linked retinitis pigmentosa (XLRP) is hampered by its genetic heterogeneity, while a clinical subdivision is almost impossible to make. So far, diagnostic services have been offered only to those families in which linkage to one RP locus (RP2 or RP3) has been clearly established. In most families, however, the nature of the XLRP type cannot be distinguished on the basis of linkage analysis. Here the authors describe that in some families DNA diagnosis is nonetheless feasible, when polymorphic DNA markers are used which span the entire Xp21.1-Xcen region and when no recombination between these markers disturbs the phase.

Blotting, Southern↗
PubMed1990

Increased ampicillin resistance in Haemophilus influenzae in Northern Ireland hospitals.

Twenty-nine of one hundred and ninety-three (15%) clinical isolates of Haemophilus influenzae from Northern Ireland hospitals during 1985-1986 were found to be ampicillin resistant. This is twice the national average for the same period and 65% increase since a similar report in Northern Ireland three years previously. Computerised monitoring of routine specimens has shown this resistance level to be maintained in 1989. Susceptibility to other antimicrobials is discussed.

Adolescent↗
PubMed1990

Evaluation of two rapid methods for identifying and biotyping Haemophilus influenzae.

Several rapid method kits (one to four hours) have become available for the identification of Haemophilus and related genera. Two kits (the "Rapid NH" system and the "RIM Haemophilus" system), which include the identification and biotyping of H influenzae, were investigated for the rapid identification and biotyping of 193 isolates of H influenzae and the results compared with those obtained by more standard overnight methods. The kits were convenient to use and gave reliable and rapid speciation of all isolates. Both test systems were unreliable for biotyping: 42 isolates were wrongly biotyped by the RIM kit and 40 isolates wrongly biotyped by the rapid NH kit. It is concluded that the test kits may be useful for the rapid identification of H influenzae but that they are not reliable for the biotyping of this species.

Bacterial Typing Techniques↗
PubMed1990

Localization of the microsatellite probe DXS426 between DXS7 and DXS255 on Xp and linkage to X-linked retinitis pigmentosa.

The microsatellite marker DXS426 maps to the interval Xp21.1-Xp11.21, the chromosomal region which contains two loci for X-linked retinitis pigmentosa (XLRP; RP2 and RP3). We have refined the localization of DXS426 both physically, by mapping it to a deletion which spans the interval Xp21.3-Xp11.23, and genetically, by studying multiply informative crossovers which indicate that DXS426 lies between DXS7 and DXS255 (i.e., Xp11.4-Xp11.22). As this is the region which contains the RP2 gene, RP2 families could be identified on the basis of linkage of XLRP to DXS426. Multiply informative crossovers in two RP2 families indicate that the most likely location of the RP2 gene is between DXS426 and DXS7. DXS426 is therefore an important highly informative marker for the purposes of carrier detection and early diagnosis of RP2 and for the localization of the disease gene.

Base Sequence↗
PubMed1989

Isolation and characterization of a human variable copy number tandem repeat at Xcen-p11.22.

A subclone (M27B) has been isolated from a cosmid randomly selected from a library enriched for human X-chromosomal material. The subclone is extensively single-copy sequence, but also contains three complete copies and one partial copy of a 26-bp repeat, within which exists an inverted repeat having the potential to form a cruciform loop structure. Genomic sequences in this repeat region are apparently refractory to cloning, and rearrangements occurring during this process result in deletions. M27B detects multiple X-linked restriction fragments for a wide range of enzymes including MspI and HpaII. We have assigned the locus recognized by the probe (DXS255) to Xcen-Xp11.4 by mapping with a somatic cell hybrid panel and further refined its localization to Xp11.22 by in situ hybridization. The repeat sequence that is presumed to be responsible for the hypervariability observed does not show close similarity to other variable copy number tandem repeats described.

Base Sequence↗
PubMed1989

Molecular characterization of human X/Y translocations suggests their aetiology through aberrant exchange between homologous sequences on Xp and Yq.

Several DNA sequences from two homologous regions, localized on the distal part of the human X chromosome short arm and on the long arm of the Y chromosome, have been hybridized to DNAs from seven human-rodent hybrids containing human X; Y translocation chromosomes. Molecular characterization of the translocated chromosomes has revealed, in all but one case, transfer of the Y cluster of sequences and complete deletion of the corresponding X-chromosomal sequences. The possible role of X/Y homology in the aetiology of X; Y translocations is proposed.

Cell Line↗