Search PubMed⌕ Search

Biomedical subjects

C Logan

Publications and source records attributed to C Logan.

At least 19 recordsLinked to original sources
PubMed1996

Rostral optic tectum acquires caudal characteristics following ectopic engrailed expression.

BACKGROUND: Expression of the homeobox-containing gene Engrailed (En) in an increasing rostral-to-caudal gradient in the dorsal mesencephalon is the earliest known marker for polarity of the chick optic tectum. In heterotopic transplantation experiments, En protein expression correlates well with the subsequent gradient of cytoarchitecture as well as the pattern of retinotectal projections. The En gradient also correlates with the expression of two putative retinal axon-guidance molecules, RAGS and ELF-1, which are Eph-like receptor tyrosine kinase ligands that may function in the establishment of retinotopic projections by excluding temporal axons from the caudal tectum. RESULTS: To examine the function of En in determining tectal polarity, we used the replication-competent retroviral vector RCAS to misexpress mouse En-1 throughout the chick tectal primordium. Our results show that the rostral portion of the tectum adopts a caudal phenotype: the gradient of cytoarchitectonic differentiation is abolished, and the molecular markers RAGS and ELF-1 are strongly expressed rostrally. In addition, cell membranes from rostral tectum of RCAS En-1-infected embryos preferentially repel temporal axons in in vitro membrane stripe assays. CONCLUSIONS: These results are consistent with a role for En in determining rostrocaudal polarity of the developing tectum. The demonstration that both RAGS and ELF-1 are upregulated following En misexpression provides a molecular basis for understanding the previous observation, also based on retrovirus-mediated En misexpression, that nasal axons form ectopic connections in rostral tectum, from which temporal axons are excluded.

Animals↗
PubMed1993

Regional assignment of the human homeobox-containing gene EN1 to chromosome 2q13-q21.

The human homeobox-containing genes EN1 and EN2 are closely related to the Drosophila pattern formation gene engrailed (en), which may be important in brain development, as shown by gene expression studies during mouse embryogenesis. Here, we have refined the localization of EN1 to human chromosome 2q13-q21 using a mapping panel of rodent/human cell hybrids containing different regions of chromosome 2 and a lymphoblastoid cell line with an interstitial deletion, del(2)(q21-q23.2). This regional assignment of EN1 increases to 22 the number of currently known genes on human chromosome 2q that have homologs on the proximal region of mouse chromosome 1.

Animals↗
PubMed1993

Two enhancer regions in the mouse En-2 locus direct expression to the mid/hindbrain region and mandibular myoblasts.

An En-2/lacZ gene fusion containing 9.5 kb of En-2 genomic DNA was capable of directing lacZ expression in an En-2-specific manner both temporally and spatially during embryogenesis and in the adult. lacZ expression was confined in the embryo to cells within the mid/hindbrain and mandibular arch regions and in the adult to cells of the molecular and granular layers of the cerebellum, and within the pons and colliculi regions. Interestingly, in the adult, transgene expression patterns within the cerebellum in two lines appeared to mark distinct anterior-posterior compartments. Analysis of the expression pattern of this transgene, in fetal and adult mice lacking a functional En-2 protein, provided evidence that the En-2 gene in mouse is not autoregulated. Deletion analysis of the En-2 genomic region and the use of a heterologous promoter identified two enhancer-containing regions of 1.5 and 1.0 kb in length, 5' of the transcribed sequences, which independently directed expression in the embryo to either the mid/hindbrain region or mandibular myoblasts, respectively. The 1.5 kb fragment contains the most anterior neural enhancer and the 1.0 kb fragment, the earliest myogenic enhancer thus far characterized. These En-2-specific regulatory regions can now be used in a biochemical analysis to identify proteins important in anterior-posterior patterning of the vertebrate CNS and in the specification of muscle identity as well as in a mutational analysis to direct expression of other developmentally important genes to these regions.

Animals↗
PubMed1992

Cloning and sequence comparison of the mouse, human, and chicken engrailed genes reveal potential functional domains and regulatory regions.

We have isolated and characterized genomic DNA clones for the human and chicken homologues of the mouse En-1 and En-2 genes and determined the genomic structure and predicted protein sequences of both En genes in all three species. Comparison of these vertebrate En sequences with the Xenopus En-2 [Hemmati-Brivanlou et al., 1991) and invertebrate engrailed-like genes showed that the two previously identified highly conserved regions within the En protein ]reviewed in Joyner and Hanks, 1991] can be divided into five distinct subregions, designated EH1 to EH5. Sequences 5' and 3' to the predicted coding regions of the vertebrate En genes were also analyzed in an attempt to identify cis-acting DNA sequences important for the regulation of En gene expression. Considerable sequence similarity was found between the mouse and human homologues both within the putative 5' and 3' untranslated as well as 5' flanking regions. Between the mouse and Xenopus En-2 genes, shorter stretches of sequence similarity were found within the 3' untranslated region. The 5' untranslated regions of the mouse, chicken and Xenopus En-2 genes, however, showed no similarly conserved stretches. In a preliminary analysis of the expression pattern of the human En genes, En-2 protein and RNA were detected in the embryonic and adult cerebellum respectively and not in other tissues tested. These patterns are analogous to those seen in other vertebrates. Taken together these results further strengthen the suggestion that En gene function and regulation has been conserved throughout vertebrate evolution and, along with the five highly conserved regions within the En protein, raise an interesting question about the presence of conserved genetic pathways.

Amino Acid Sequence↗
PubMed1992

Soft drink consumption and urinary stone recurrence: a randomized prevention trial.

The object of this study was to determine if a strong association between soft drink (soda) consumption and recurrence of urinary stone disease, found in an earlier case-control study of adult males, had a causal component. The study sample consisted of 1009 male subjects, who completed an episode of urinary stone disease, who were aged 18-75 at that time, and who reported consuming at least 160 ml per day of soft drinks. Half of the subjects were randomized to refrain from consuming soft drinks, while the remaining subjects served as controls. The intervention group had an observed 6.4% advantage in actuarial 3 yr freedom from recurrence (p = 0.023 one-sided) over the control group. One important secondary finding was that for those who reported at the time of the index stone that their most consumed drink was acidified by phosphoric acid but not citric acid, the experimental group had a 15% higher 3 yr recurrence-free rate than the controls, p = 0.002, while for those who reported at the time of the index stone that their most consumed drink was acidified by citric acid with or without phosphoric acid, the experimental group had a similar 3 yr recurrence-free rate to the controls, p = 0.55. This interaction was significant, p = 0.019.

Actuarial Analysis↗
PubMed1989

Chromosomal localization of the human homeo box-containing genes, EN1 and EN2.

The human homologs of the mouse homeo box-containing genes, En-1 and En-2, which show homology to the Drosophila engrailed gene, have been isolated. The human EN1 gene was mapped to chromosome 2 by analysis of mouse-human somatic cell hybrids. The human EN2 gene was localized to chromosome 7, 7q32-7qter, by analysis of rodent-human somatic cell hybrids and cell lines carrying portions of chromosome 7.

Animals↗
PubMed1988

Treatment of Paget's disease of bone with salmon calcitonin nasal spray.

Subcutaneous daily or bidaily administration of synthetic salmon calcitonin is an effective form of therapy for Paget's disease, but the requirement for parenteral injection deters geriatric patients from using the drug. This study compares a new intranasal preparation of salmon calcitonin to subcutaneous drug in 18 patients with Paget's disease using two different protocols. In the first protocol, 15 patients not previously treated with salmon calcitonin were given the agent for 3 months by either the intranasal or subcutaneous route. Seven patients treated with intranasal calcitonin had a mean fall in the serum alkaline phosphatase of 33% over a 3-month period compared to a fall of 40% in the subcutaneously treated group; the difference between the two treatment groups was not statistically significant. In the second protocol, three patients previously stabilized on subcutaneous calcitonin were switched to the nasal spray with no subsequent change in alkaline phosphatase values during 6 months of treatment. These results demonstrate that intranasal salmon calcitonin is effective in lowering the serum alkaline phosphatase in Paget's disease. Ease of administration and patient acceptance make intranasal calcitonin a reasonable alternative for geriatric patients.

Administration, Intranasal↗
PubMed1987

A survey of National Health Service dietetics in Scotland.

This report summarizes the main results of a survey completed by every dietitian employed by the National Health Service in Scotland on October 31, 1983. There are currently no norms or standards for dietetic services in the United Kingdom, but these results present an opportunity for comparison among health boards. Staffing is compared with 1977 figures and time spent in different activities is shown.

Dietetics↗
PubMed1986

Linkage analysis of polymorphisms within the DNA fragment XJ cloned from the breakpoint of an X;21 translocation associated with X linked muscular dystrophy.

Cloning of a DNA segment including the translocation breakpoint in a female with an X;21 translocation and X linked muscular dystrophy has led to identification of three subclones which detect polymorphic markers. The alleles of these markers, XJ1 X 1, XJ1 X 2, and XJ2 X 2, are in strong linkage disequilibrium. Linkage analysis in 31 families with Duchenne or Becker muscular dystrophy has shown recombination within the XJ segment in one case, and recombination of DMD with both the XJ segment and the pERT87 segment in a second, but has revealed no recombination between the XJ and pERT87 segments. The XJ markers increase the proportion of DMD and BMD families that are informative for carrier detection and prenatal diagnosis, but in view of the risk of recombination they must be used with caution. The site(s) of the DMD mutation(s) relative to the XJ and pERT87 markers, and the detailed molecular structure of the DMD region, remain to be determined.

Alleles↗
PubMed1977

The evaluation of sexual health services in a medical setting.

An interdisciplinary Sexual Health Services unit has been established at the University of Minnesota Medical School that offers counseling and treatment programs for a wide variety of sex-related concerns and problems. The programs are based on the principles of responsibility for self, permission to be sexual, the use of reeducation, the facilitation of increased awareness in clients, and structured behavior change. The programs have been evaluated according to client satisfaction with the extent to which they have met pretreatment goals and according to results of pre/posttesting with objective instruments. One year follow-up results from 131 clients and immediate posttreatment results from 411 clients show positive change in a large majority of cases.

Behavior Therapy↗
PubMedDate not supplied

Cloning of the breakpoint of an X;21 translocation associated with Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder which affects approximately 1 in 3,300 males, making it the most common of the neuromuscular dystrophies. The biochemical basis of the disease is unknown and as yet no effective treatment is available. A small number of females are also affected with the disease, and these have been found to carry X; autosome translocations involving variable autosomal sites but always with a breakpoint within band Xp21 of the X chromosome (implicated by other kinds of genetic evidence as the site of the DMD lesion). In these female patients the normal X chromosome is preferentially inactivated, which it is assumed silences their one normal DMD gene, leading to expression of the disease. In one such affected female the autosomal breakpoint lies in the middle of the short arm of chromosome 21, within a cluster of ribosomal RNA genes. Here we have used rRNA sequences as probes to clone the region spanning the translocation breakpoint. A sequence derived from the X-chromosomal portion of the clone detects a restriction fragment length polymorphism (RFLP) which is closely linked to the DMD gene and uncovers chromosomal deletions in some male DMD patients.

Animals↗