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Biomedical subjects

A M Morrison

Publications and source records attributed to A M Morrison.

12 recordsLinked to original sources
PubMed2000

ESOP-1, a secreted protein expressed in the hematopoietic, nervous, and reproductive systems of embryonic and adult mice.

To isolate soluble factors expressed in early phases of hematopoietic differentiation, we applied the signal sequence trap method to the in vitro murine hematopoietic differentiation system, in which ES cells are cocultured with OP-9 stroma cells. This strategy allowed us to isolate cDNA for a secreted protein, ESOP-1, of 160 amino acids, the sequence of which shows 64% identity with human ESOP-1/MD-2. ESOP-1 mRNA was highly expressed in the mouse embryos at 7.5 days after coitus. Expression of the ESOP-1 mRNA and protein was shown in the embryonic and adult hematopoietic system. In addition, the ESOP-1 protein was found in the yolk sac-blood islands, the developing nervous system, and the adult reproductive system. These results suggest that ESOP-1 may play some roles in the development or maintenance of hematopoietic, nervous, and reproductive systems.

Amino Acid Sequence↗
PubMed1999

Comprehensive assessment of retinal, choroidal and retrobulbar haemodynamics during blood gas perturbation.

BACKGROUND: A study was performed to evaluate the effect of isoxic hypercapnia on ocular haemodynamics using colour Doppler imaging (CDI), scanning laser Doppler flowmetry (SLDF) and ocular blood flow (OBF) tonography. METHODS: Measurements were taken for one eye of each of 14 healthy subjects (mean age 27 +/- 6 years) during breathing of room air and then during isoxic hypercapnia (breathing CO2 and room air). Using CDI, blood flow velocities and resistance indices were determined for the ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCAs). Using SLDF a 10 x 10 pixel frame was used to measure blood flow, volume and velocity in each quadrant of the peripapillary retina. Pulsatile ocular blood flow (POBF) was measured using the OBF tonograph. RESULTS: Using CDI, peak systolic and end diastolic velocities increased and resistance index decreased significantly in the SPCAs during hypercapnia. Using SLDF, blood flow, volume and velocity increased significantly during hypercapnia in the superior temporal quadrant of the peripapillary retina. No significant difference was observed between baseline and hypercapnia for POBF. CONCLUSIONS: Isoxic hypercapnia resulted in an increase in peripapillary retinal and SPCA blood flow parameters as determined by SLDF and CDI respectively. This implies the presence of autoregulatory activity in these vasculatures. These findings may be of significance in the pathogenesis of ocular disease such as glaucoma where autoregulation is thought to be compromised.

Adolescent↗
PubMed1998

Deregulated PAX-5 transcription from a translocated IgH promoter in marginal zone lymphoma.

The PAX-5 gene codes for the transcription factor BSAP, which is expressed throughout B-cell development. Although loss-of-function mutation in the mouse showed an essential role for Pax-5 in early B lymphopoiesis, gain-of-function mutations have implicated the human PAX-5 gene in the control of late B-cell differentiation. PAX-5 (on 9p13) has been involved together with the immunoglobulin heavy-chain (IgH) gene (on 14q32) in the recurring t(9;14)(p13;q32) translocation that is characteristic of small lymphocytic lymphoma with plasmacytoid differentiation. Here we have characterized a complex t(2;9;14)(p12;p13;q32) translocation present in a closely related non-Hodgkin's lymphoma referred to as splenic marginal zone lymphoma (MZL). In this MZL-1 translocation, the two promoters of PAX-5 were replaced on the derivative chromosome 14 by an immunoglobulin switch Smicro promoter that was linked to the structural PAX-5 gene upstream of its translation initiation codon in exon 1B. Expression analyses confirmed that PAX-5 transcription was upregulated due to efficient initiation at the Smicro promoter in the malignant B lymphocytes of patient MZL-1. For comparison we have analyzed PAX-5 expression in another B-cell lymphoma, KIS-1, indicating that transcription from the distal PAX-5 promoter was increased in this tumor in agreement with the previously characterized translocation of the immunoglobulin Emicro; enhancer adjacent to PAX-5 exon 1A. In both lymphomas, the J-chain gene, which is thought to be under negative control by BSAP, was not expressed, whereas transcription of the putative target gene p53 was unaffected by PAX-5 overexpression. Together these data indicate that the t(9;14)(p13;q32) translocation contributes to lymphoma formation as a regulatory mutation that leads to increased PAX-5 expression in late B-cell differentiation due to promoter replacement or enhancer insertion.

Aged↗
PubMed1998

Identification of BSAP (Pax-5) target genes in early B-cell development by loss- and gain-of-function experiments.

The Pax-5 gene codes for the transcription factor BSAP which is essential for the progression of adult B lymphopoiesis beyond an early progenitor (pre-BI) cell stage. Although several genes have been proposed to be regulated by BSAP, CD19 is to date the only target gene which has been genetically confirmed to depend on this transcription factor for its expression. We have now taken advantage of cultured pre-BI cells of wild-type and Pax-5 mutant bone marrow to screen a large panel of B lymphoid genes for additional BSAP target genes. Four differentially expressed genes were shown to be under the direct control of BSAP, as their expression was rapidly regulated in Pax-5-deficient pre-BI cells by a hormone-inducible BSAP-estrogen receptor fusion protein. The genes coding for the B-cell receptor component Ig-alpha (mb-1) and the transcription factors N-myc and LEF-1 are positively regulated by BSAP, while the gene coding for the cell surface protein PD-1 is efficiently repressed. Distinct regulatory mechanisms of BSAP were revealed by reconstituting Pax-5-deficient pre-BI cells with full-length BSAP or a truncated form containing only the paired domain. IL-7 signalling was able to efficiently induce the N-myc gene only in the presence of full-length BSAP, while complete restoration of CD19 synthesis was critically dependent on the BSAP protein concentration. In contrast, the expression of the mb-1 and LEF-1 genes was already reconstituted by the paired domain polypeptide lacking any transactivation function, suggesting that the DNA-binding domain of BSAP is sufficient to recruit other transcription factors to the regulatory regions of these two genes. In conclusion, these loss- and gain-of-function experiments demonstrate that BSAP regulates four newly identified target genes as a transcriptional activator, repressor or docking protein depending on the specific regulatory sequence context.

Animals↗
PubMed1998

Loss- and gain-of-function mutations reveal an important role of BSAP (Pax-5) at the start and end of B cell differentiation.

Pax-5 codes for the transcription factor BSAP which is expressed throughout B cell development except in terminally differentiated plasma cells. Gene targeting experiments in the mouse revealed a differential dependency of fetal and adult B-lymphopoiesis on this transcription factor. BSAP is required for B-lineage commitment in the fetal liver and for progression beyond an early pro-B cell stage in adult bone marrow. The characterization of Pax-5-deficient pro-B cells demonstrated an important role of BSAP in the regulation of the CD19, mb-1 (Ig alpha) and N-myc genes as well as in the developmental pathway controlling VH-to-DHJH recombination at the immunoglobulin heavy-chain (IgH) locus. The human PAX-5 gene was recently shown to participate together with the IgH locus in the chromosomal translocation t(9;14)(p13;q32). This translocation is characteristic of a small subset of non-Hodgkin lymphomas exhibiting plasmacytoid differentiation. The translocated PAX-5 gene is deregulated by the insertion of IgH regulatory elements into its 5' region, which may contribute to tumorigenesis by interfering with the shut-down of PAX-5 transcription and thus with the completion of plasma cell differentiation.

Adult↗
PubMed1996

A novel nonanticoagulant heparin prevents vascular endothelial cell dysfunction during hyperdynamic sepsis.

Although a novel nonanticoagulant heparin (i.e., GM1892) produces various beneficial effects after hemorrhage and resuscitation, it remains unknown whether this agent has any salutary effects on the depressed vascular endothelial cell function during sepsis. To determine this, rats were subjected to sepsis by cecal ligation and puncture (CLP). At 1 h after CLP, GM1892 (7 or 14 mg/kg body wt), conventional heparin (7 or 14 mg/kg), or an equal volume of saline was administered intravenously. At 5 h after CLP (i.e., hyperdynamic sepsis), the thoracic aortae were isolated and placed in organ chambers. Dose-response relaxation curves were determined for acetylcholine (ACh; 10(-8) to 10(-5) M), which stimulates endothelial nitric oxide production, and for nitroglycerine (10(-9) to 10(-6) M), which directly provides nitric oxide in vivo. ACh-induced relaxation was depressed at 5 h after CLP while there was no significant alteration in nitroglycerine-induced relaxation. Treatment with 14 mg/kg GM1892 or 14 mg/kg heparin (but not with 7 mg/kg GM1892 or 7 mg/kg heparin), however, prevented the decrease of ACh-induced relaxation. Thus, GM1892 (which does not possess any significant anticoagulant properties) at the higher dosage appears to be useful for maintaining vascular endothelial cell function during hyperdynamic sepsis.

Acetylcholine↗
PubMed1993

Familial Hirschsprung's disease: 20 cases in 12 kindreds.

This report describes 20 infants and children with a family history of Hirschsprung's disease in 12 kindreds. A total of 260 patients were treated for Hirschsprung's disease (1972 to 1991), yielding a familial incidence of 8%. There were no families with consanguineous marriage. Sixteen patients were male and four were female. The mean age at diagnosis was 18 days. Clinical presentation included delayed passage of meconium in 15, abdominal distention in 11, vomiting in 9, feeding abnormalities in 3, and complete bowel obstruction in 1. Associated congenital anomalies occurred in 25% of the patients. The extent of aganglionosis was rectal in 4, sigmoid in 4, left colon in 2, transverse or right colon in 2, and total colonic in 8. Enterocolitis occurred in 7 patients (35%); 2 at diagnosis, 2 after an ostomy, and 3 after a pull-through procedure. There were no deaths associated with enterocolitis. All patients had a proximal diverting colostomy or ileostomy, and 19 of 20 underwent a definitive pull-through procedure. Three patients were lost to follow-up and one patient died of complications of multiple congenital anomalies unassociated with Hirschsprung's disease. Of the remaining 16 patients, all of whom have undergone a pull-through procedure, 11 are fully continent, 2 have nighttime soiling, 2 are too young to evaluate bowel function, and 1 still has an ostomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Distribution↗
PubMed1992

Hirschsprung's disease. Evaluation of mortality and long-term function in 260 cases.

This report describes 260 patients treated for Hirschsprung's disease. There were 213 boys (82%) and 47 girls (18%). Age at diagnosis was younger than 30 days in 106 patients (41%), 1 month to 1 year in 90 patients (35%), and older than 1 year in 64 patients (25%). Diagnosis was achieved with barium enema and rectal biopsy. Aganglionosis involved the rectum or rectosigmoid in 174 patients (67%), the left colon in 38 patients (15%), and the proximal colon in 23 patients (9%); 25 patients (9%) had total colonic aganglionosis. Enterocolitis occurred in 47 cases (18%). Following an initial colostomy or ileostomy, a definitive pull-through procedure was performed in 247 patients (95%) (modified Duhamel in 185, Soave in 25, Swenson procedure in 15, and anomyectomy/sphincterotomy in 22); the overall survival rate was 93.8% (244 of 260 patients). An increased mortality was associated with Down syndrome, total colonic aganglionosis, and enterocolitis. Long-term follow-up (mean, 6 years 10 months) was available in 103 patients who underwent a Duhamel procedure. Sixty-seven (65%) had normal bowel function, 28 (27%) occasionally used enemas or stool softeners, and eight (8%) had severe constipation or soiling. Bowel habits improved with time and were considered normal in 58% of patients at less than 5 years of follow-up and in 88% of patients at more than 15 years of follow-up. The Duhamel operation is a very effective definitive procedure for Hirschsprung's disease. Long-term follow-up is an important component of patient care.

Anastomosis, Surgical↗
PubMed1983

Iris prolapse following cataract surgery.

6,485 cases of cataract extraction are reviewed. Iris prolapse was a post-operative complication in 32 cases. (Incidence = 0.49 per cent). It is a relatively uncommon complication of present day cataract surgery, and it is postulated that iris prolapse results from transient pupillary block, in the post-operative period.

Cataract Extraction↗