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Biomedical subjects

J Carton

Publications and source records attributed to J Carton.

13 recordsLinked to original sources
PubMed2001

Downstream changes in the transport and storage of sediment-associated contaminants (P, Cr and PCBs) in agricultural and industrialized drainage basins.

Samples of suspended, floodplain and channel bed sediment have been used to examine downstream changes in ediment-associated contaminant transport and storage in contrasting rivers in Yorkshire, UK. The concentrations of hosphorus, chromium and selected PCBs associated with sediment in the River Aire and its main tributary, the River Calder, which drain an urbanized and industrialized catchment, are considerably higher than those in the relatively unpolluted River Swale, which drains an agricultural catchment. Concentrations of sediment-associated contaminants in the Aire/Calder system increase downstream, reflecting the location of urban and industrial areas in the middle and lower reaches, and the location of point source inputs, such as sewage treatment works. The ontaminant concentrations associated with floodplain and channel bed sediment in the Rivers Aire and Calder are high, particularly in the lower reaches. This, combined with measurements of sediment storage on the floodplain and channel bed, indicate that significant storage of sediment-associated contaminants occurs in the Rivers Aire and Calder.

Agriculture↗
PubMed2000

Serine palmitoyltransferase regulates de novo ceramide generation during etoposide-induced apoptosis.

The de novo pathway of sphingolipid synthesis has been identified recently as a novel means of generating ceramide during apoptosis. Furthermore, it has been suggested that the activation of dihydroceramide synthase is responsible for increased ceramide production through this pathway. In this study, accumulation of ceramide mass in Molt-4 human leukemia cells by the chemotherapy agent etoposide was found to occur primarily due to activation of the de novo pathway. However, when the cells were labeled with a substrate for dihydroceramide synthase in the presence of etoposide, there was no corresponding increase in labeled ceramide. Further investigation using a labeled substrate for serine palmitoyltransferase, the rate-limiting enzyme in the pathway, resulted in an accumulation of label in ceramide upon etoposide treatment. This result suggests that the activation of serine palmitoyltransferase is the event responsible for increased ceramide generation during de novo synthesis initiated by etoposide. Importantly, the ceramide generated from de novo synthesis appears to have a distinct function from that induced by sphingomyelinase action in that it is not involved in caspase-induced poly (ADP-ribose)polymerase proteolysis but does play a role in disrupting membrane integrity in this model system. These results implicate serine palmitoyltransferase as the enzyme controlling de novo ceramide synthesis during apoptosis and begin to define a unique function of ceramide generated from this pathway.

Acyltransferases↗
PubMed2000

Menstrual cycle dependent fluctuations in NK and T-lymphocyte subsets from non-pregnant human endometrium.

PROBLEM: To establish the relative proportions of endometrial lymphocyte subpopulations during the menstrual cycle. METHOD OF STUDY: Lymphocytes were investigated by flow cytometry, during the early proliferative (EP), late proliferative (LP), early secretory (ES) and late secretory (LS) phases of the menstrual cycle. RESULTS: Between the LP and LS phases, there was an increase in NK cells from 26.4% to 83.2% (P = 0.0017) of the CD45+ population. T cells decreased from 55.06% to 6.7% (P = 0.0017). Within the T-cell population, CD8+ cells decreased significantly from 63.0% in the LP phase to 54.2% in the LS phase (P = 0.04). In contrast, potential regulatory populations such as double negative (DN) T cells CD3+CD4-CD8- and natural T cells (NT) CD3+CD56+, increased significantly in the LS phase (P = 0.05; P = 0.03). gammadelta T cells, predominantly of the DN and NT phenotypes remained consistently low at all stages of the cycle (2.34%). CONCLUSION: Endometrial lymphocyte fluctuations during the menstrual cycle may reflect hormonal regulation of maternal immunity, thereby promoting tolerance at the time of implantation.

Adult↗
PubMed1999

Optimisation of a technique for isolating lymphocyte subsets from human endometrium.

Human endometrium is a rich source of lymphocytes which may have unique immunoregulatory functions. The aim of this study was to compare current procedures for endometrial tissue disaggregation, and optimise a method for isolation of endometrial lymphocytes. Tissue was obtained from 41 women undergoing elective hysterectomy or dilation and curettage (D&C) for reasons of benign non-endometrial pathology. Specimens were exposed to reduction/chelation, mechanical or enzymatic disruption. Optimal single cell suspensions of high yields (mean 8.8 x 10(6) range 3.5-18 x 10(6)lymphs) and good viability (60%) were obtained, using a combination of collagenase IV (200 U/ml) and DNase I (35 U/ml). Suspensions were further purified by density gradient centrifugation. Multi-colour flow cytometry was used for analysis of endometrial lymphocyte subsets. Cell suspensions were stained with mAbs specific for CD3, CD4, CD8, CD56, CD45 and CD14, and it was clearly shown that the developed method had no effect on surface glycoprotein expression. Phenotypic analysis revealed consistent populations of endometrial large granular lymphocytes (CD56+CD3-) 54.16%, and T-cells (CD3+) 37.73%. This technique was applicable to the characterisation of T-cell populations, including CD8+ (56.6%), CD4+ (44.0%), and particularly smaller populations of CD4+CD8+(3.56%), CD4-CD8-(3.34%) and CD56+(6.3%) due to it's sensitivity. In conclusion, optimised enzymatic digestion, in combination with flow cytometry provides an effective method for phenotypic examination of small endometrial lymphocyte subpopulations.

Adult↗
PubMed1998

CD4+ CD8+ and CD8alpha+ beta- T lymphocytes in human small intestinal lamina propria.

OBJECTIVE: To examine CD8 expression by T-lymphocyte subpopulations from disease-free human lamina propria. METHODS: Single-cell suspensions were prepared from the epithelial layer and the lamina propria of small intestinal biopsies obtained endoscopically from disease-free patients. Monoclonal antibodies against CD3, CD4, CD8, CD56, CD8alphabeta, CD8alpha, TCR alphabeta and TCR gammadelta were used for dual and three-colour flow cytometric analysis. RESULTS: In addition to classical CD4+ and CD8+ T lymphocytes a substantial proportion of lamina propria T lymphocytes were CD4+ CD8+ or 'double positive' (mean 14%, range 4-26%). This population was significantly lower in the epithelial layer of the same patients (mean 7%, range 3-21%, P < 0.007). Three-colour flow cytometric analysis revealed that expression of the CD8 molecule on double positive T cells in the lamina propria was limited to the CD8alpha chain. Furthermore, of the CD8+ population, CD8+ T cells which only expressed the alpha chain were present in greater numbers in the lamina propria (mean 35%, range 14-54%) than in the epithelial layer (mean 18%, range 5-37%, P < 0.02). NK (CD56+) cells were not detected and few gammadeltaTCR+ T lymphocytes were detected in the lamina propria (mean 2%, range 0.5-6.6%) when compared with the epithelial layer (mean 8%, range 0.2-14%, P < 0.008). CONCLUSION: A significant population of CD4+ CD8alpha+ T lymphocytes which are CD8beta chain negative have been detected in the intestinal lamina propria. These cells form a more significant component of the lamina propria than the epithelial layer T-cell repertoire and may have a unique function in intestinal immunoregulation.

Adolescent↗
PubMed1991

[Non-cardiogenic pulmonary edema after transfusion of plasma containing an anti-HLA-B21 antibody].

A patient with a von Willebrand factor deficiency received three units of fresh frozen plasma during a postoperative period. During the last unit transfusion she developed a severe respiratory distress and non cardiac pulmonary edema was diagnosed based upon the clinical, radiological and hemodynamic findings. Reintubation and mechanical ventilation with end-expiratory pressure were instituted leading to a complete and rapid recovery within 48 h. The serum from the last plasma donor contains an anti-HLA-B21 lymphocytotoxic antibody that did agglutinate neutrophils from HLA-B21 positive individuals. The patient's HLA type was B21. The concerned donor was a IVpar Igeste female. Two problems are evoked by this observation with regard to transfusion: first, fresh-frozen plasma was used as an inappropriate treatment for a coagulating factor deficiency, second, exclusion of this donor from a classical blood donation is needed.

Adult↗
PubMed1988

Nucleotide sequence of the middle dsRNA segment of bacteriophage phi 6: placement of the genes of membrane-associated proteins.

The genome of the lipid-containing bacteriophage phi 6 contains three segments of double-stranded RNA. We have determined the nucleotide sequence of cDNA derived from the middle-size RNA segment. The coding sequences of three proteins on this segment were identified on the basis of size and the correlation of predicted N-terminal amino acid sequences with those found through the analysis of isolated proteins. In contrast to our results with the small phi 6 dsRNA segment, the open reading frames are not tightly clustered. The homologous terminal noncoding regions between the middle and small dsRNA segments are found to be more extensive than RNA sequencing had previously indicated.

Amino Acid Sequence↗
PubMed1988

Nucleotide sequence of the large double-stranded RNA segment of bacteriophage phi 6: genes specifying the viral replicase and transcriptase.

The genome of the lipid-containing bacteriophage phi 6 contains three segments of double-stranded RNA. We determined the nucleotide sequence of cDNA derived from the largest RNA segment (L). This segment specifies the procapsid proteins necessary for transcription and replication of the phi 6 genome. The coding sequences of the four proteins on this segment were identified on the basis of size and the correlation of predicted N-terminal amino acid sequences with those found through analysis of isolated proteins. This report completes the sequence analysis of phi 6. This constitutes the first complete sequence of a double-stranded RNA genome virus.

Amino Acid Sequence↗