Search PubMed⌕ Search

Biomedical subjects

N Mortensen

Publications and source records attributed to N Mortensen.

At least 37 records · Page 2Linked to original sources
PubMed1996

Intestinal permeability in the ileal pouch.

BACKGROUND: Villous atrophy, mucin changes ('colonic metaplasia'), and chronic inflammation occur to varying degrees in all patients with ileal pouchanal anastomosis whereas acute inflammation (pouchitis) affects a subgroup of patients with prior ulcerative colitis. AIM: To measure epithelial barrier function looking for possible functional adaptation in ileal 'pouch' mucosa. PATIENTS: Patients with an ileal pouch prior to ileostomy closure (n = 12), functioning pouch (n = 14), pouchitis (n = 8), and ulcerative colitis (n = 12) were assessed. METHODS: 51Cr-EDTA was administered into the 'pouch' or rectum and urinary recovery over 24 hours was taken as an indication of permeability (barrier function). Histological analysis of 'pouch' biopsy specimens was undertaken. RESULTS: Mucosal permeability is decreased from median 9.4% (range 5.4% to 39.1%) to 1.4% (range 0.38% to 2.2%) after ileostomy closure (p < 0.002) with levels being negatively correlated with two histological parameters of colonic metaplasia-mucin changes (p = 0.03) and villous atrophy (p = 0.05). Pouchitis was associated with increased permeability 5.9% (1.9% to 19.5%) compared with healthy 'pouch' 1.4% (0.35 to 2.2%) (p < 0.006). CONCLUSION: Despite the presence of chronic inflammation in the mature 'pouch' functional adaptation with reduced permeability occurs in conjunction with colonic metaplasia.

Biopsy↗
PubMed1996

Pigbel-like syndrome in a vegetarian in Oxford.

Enterocolitis necroticans or pigbel is a rare condition characteristically affecting chronically malnourished people who abruptly increase their intake of protein. The classic presentation of the disease as seen in the highlands of Papua New Guinea is that of a necrotising enterocolitis after the ritual ingestion of contaminated pork. In this context, the presentation of the same disease in a well nourished white vegetarian in Oxford was all the more intriguing.

Adult↗
PubMed1994

Loss of major histocompatibility complex-encoded transporter associated with antigen presentation (TAP) in colorectal cancer.

Presentation of endogenous antigenic peptides to cytotoxic T lymphocytes (CTLs) is mediated by the major histocompatibility complex (MHC) class I molecules. These antigenic peptides derived from the cytoplasmic protein pool are transported by the recently described MHC-encoded transporters (TAP1 and TAP2) into a pre-Golgi region where they take part in the assembly of MHC class I molecules. Using an affinity-purified polyclonal antibody (AK1.7) for TAP1, we analyzed 81 colorectal carcinomas, 32 adenomas, and the respective nonneoplastic mucosa. Loss of the transporter molecule (TAP1) was observed in 14% (11 of 81) of the carcinomas, either complete (7 of 11) or focal (4 of 11), whereas adenomas and normal mucosa were always positive. This study adds further information to the understanding of the mechanisms related to the defective presentation of the MHC class I molecules by tumor cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Nerve mediated relaxation of the human internal anal sphincter: the role of nitric oxide.

The aim of this study was to determine if nitric oxide (NO) is the non-adrenergic, non-cholinergic neurotransmitter, released by enteric inhibitory nerves, which mediates relaxation of the human internal anal sphincter. Isolated muscle strips were mounted for isometric tension recording in superfusion organ baths. Sodium nitroprusside, an exogenous donor of NO, relaxed the strips in a concentration dependent manner. In the presence of atropine and guanethidine, transmural field stimulation produced tetrodotoxin sensitive relaxations, which were inhibited in a dose dependent and enantiomer specific manner by antagonists of NO synthase; completely by L-nitroarginine and partially by L-N-monomethyl arginine. The effect of these antagonists was reversed by L-arginine but not D-arginine. Oxyhaemoglobin, a scavenger of nitric oxide, also abolished the relaxations but methaemoglobin had no such effect. These results strongly suggest that NO is, or is very closely associated with, the non-adrenergic, non-cholinergic neurotransmitter mediating neurogenic relaxation of the human internal anal sphincter.

Aged↗
PubMed1993

p53 expression in colorectal adenomas.

To assess the expression of p53 in premalignant lesions, we examined by immunohistochemistry benign colorectal adenomas (n = 72, measuring more than 6 mm and less than 95 mm in diameter) from patients without (group I, n = 23) or with (group II, n = 49) concurrent sporadic colorectal carcinomas. Using a panel of three monoclonal antibodies (PAb 240, PAb 421, PAb 1801) and two polyclonal antibodies (CM1, C19) immunohistological staining was demonstrated in 26% of the cases (19 of 72 adenomas, 7 of 23 from group I and 12 of 49 from group II). In the majority of the cases, p53 positive foci in the adenomas occurred in the most dysplastic areas, although focal positivity was detected in glands that were histologically normal. Expression of p53 protein was also detected in 21 of 30 (70%) colorectal carcinomas of group II. In two cases focal positive staining was observed in the polyps but not in the concurrent carcinomas. Non-neoplastic colonic mucosa and stromal lymphoid cells were negative in all cases examined. Over-expression of p53 in neoplastic tissues detected by immunocytochemistry is generally believed to correlate with the presence of mutation in the gene. This may not be an absolute rule, because in some hemopoietic malignancies, there is evidence that p53 protein may be detectable in the absence of an underlying mutation. These findings therefore represent the highest incidence in colorectal adenomas of abnormalities in the p53 protein expression, probably largely due to underlying mutations. This study also suggests that immunocytochemical demonstration of p53 protein may be a suitable method for the routine detection of subpopulations of cells which, by clonal expansion, could acquire a growth advantage within an adenoma during the neoplastic process.

Adenoma↗
PubMed1992

Loss of HLA class-I alleles, heavy chains and beta 2-microglobulin in colorectal cancer.

Using immunohistochemical methods, we have analysed colorectal biopsies of normal mucosa, metaplastic polyps (5 cases), adenomas (15 cases) and adenocarcinomas (70 cases) with 13 monoclonal antibodies (MAbs) to allelic products of the HLA-A, B, C loci. Nine of the 70 carcinomas showed total loss of HLA Class-I molecules due to an underlying defect regarding not only the expression of beta 2-microglobulin (beta 2-m), but also the heavy chains of HLA A, B and C loci, or both. Much commoner was a loss of one or more Class-I alleles as follows: A1/Aw36 (completely lost in 4 of 29 cases and focally lost in another 2), A2 (in 1 of 37 cases), A3 (in 2 of 14 cases), A1 1/28/31/33 (in 3 of 11 cases), B7 (in 3 of 13 and focally in 1 other case), B17 (in 1 case), Bw4 (in 8 of 45 and focally in another 6), Bw6 (in 9 of 62 and focally in another 3). Focal selective loss (Bw6 and a combined A1-Bw6), was observed in 2 adenomas. Normal colonic mucosa, as well as stromal and lymphoid cells present between the neoplastic glands, were studied in each case as a control. A particular allele was only considered to be lost by the malignant cells if it was still expressed on these adjacent tissues.

Alleles↗
PubMed1992

Management variability in surgery for colorectal emergencies.

A prospective study was made of 92 patients who underwent emergency colorectal surgery during a 1-year period. A dedicated emergency theatre allowed half of the patients to be operated on between 09.00 and 17.00 hours with greater seniority of operating surgeons. The overall mortality rate was 14 per cent and the primary resection rate was 79 per cent. The mortality rate was 12 per cent for right-sided resection with anastomosis and 24 per cent for left-sided resection without anastomosis, including those undergoing Hartmann's procedure which had a 35 per cent mortality rate. Immediate left-sided anastomosis was performed safely in all 14 patients in whom it was attempted. Firms headed by consultants with and without a special interest in colorectal disease made differing use of primary resection and immediate anastomosis (67 versus 41 per cent, P less than 0.05) and Hartmann's (7 versus 25 per cent, P less than 0.05) and non-resectional (15 versus 29 per cent, P not significant) procedures. Retrospective surveys of perioperative deaths examine inadequate management and subsequent mortality rates, but do not reveal the significant morbidity rate that occurs in survivors. This audit revealed significant differences in the management of patients with colorectal emergencies between firms headed by specialist and non-specialist consultants. In order to minimize these differences we believe that recent advances in colorectal practice should be included in the training of all surgeons.

Adult↗
PubMed1992

Interleukin-4 receptor and epidermal growth factor receptor expression in colorectal cancer.

Interleukin-4 receptor (IL-4R) and Epidermal Growth Factor receptor (EGFR) were assessed as factors associated with adenoma-carcinoma progression in colorectal cancer and tumour invasion. A monoclonal antibody (MR6) was applied to detect IL-4R in: metaplastic polyps (five cases), adenomas (15 cases), and carcinomas (44 adenocarcinomas and one squamous cell). Positive labelling was obtained in all polyps, adenomas and in 40/45 carcinomas. Normal colonic mucosa of these patients, as well as macrophages and lymphocytes infiltrating the tumour stroma, were also positively labelled with MR6. Four out of five poorly differentiated adenocarcinomas did not show IL-4 receptor expression. No significant correlation was found with tumour size, lymph node stage and IL-4 receptor expression. On the above specimens a parallel detection of epidermal growth factor receptors (EGFR) by a monoclonal antibody (EGFR 1) was carried out. Expression of EGFR was found in 14/20 polyps and in 22/45 carcinomas. All but one of the EGFR positive malignant tumours showed coexpression of IL-4 receptor. Lymph node involvement by tumour cells was detected in 25 out of 45 patients. Eighteen of these 25 cases were positive with EGFR1.

Adenocarcinoma↗
PubMed1992

Restorative proctocolectomy--the pouch operation: good or bad?

Restorative proctocolectomy is now the procedure of choice for patients requiring surgery for ulcerative colitis and some for familial adenomatosis. The indications for operation are being refined, and technically the procedure has been simplified. Although it avoids ileostomy, it does not restore normality. Stool frequency, continence problems, and pouchitis can all spoil a good result. In spite of these shortcomings, it represents a major advance.

Adenomatous Polyposis Coli↗
PubMed1991

The anal continence plug: a disposable device for patients with anorectal incontinence.

Anorectal incontinence is most commonly found in the elderly, but colorectal surgeons now see an increasing number of younger patients with this condition. Although medical and surgical treatments are available, a proportion of patients remain refractory to therapy. We investigated the efficacy of three designs of anal continence plug. 8 women and 2 men (mean age, 52 years) who were incontinent to both liquid and solid stool tested each plug for three consecutive weeks. 1 patients withdrew from the study. The median weartime for the optimum plug design was 12 h, and there were no episodes of incontinence in 82% of the periods during which the plug was in place. Patients required a median of eleven plugs per week, and in 82% of cases insertion was as easy as with a suppository. Plugs may have a place in the management of patients with anorectal incontinence.

Adolescent↗
PubMed1991

How countries with more resources can help.

Countries with more resources have more experience of hospital-associated infections than countries with fewer resource. The value of infection control programmes based on incidence or prevalence studies is understood. Helping countries with fewer resources means sharing experience as well as resources. Documentation of the magnitude of hospital-associated infections has been used in many countries to create interest and generate funds from authorities, hospital managers and within the hospital world. Sharing resources could be in the form of financial support for participation of experts in training courses. Attendance at such training courses could be based upon local surveys of hospital-associated infections and could result in the production of local guidelines for surveillance and control of hospital-associated infections. Knowledge of the local situation is a sine qua non for this type of help to be useful.

Communicable Disease Control↗
PubMed1991

Effects of the faecal stream and stasis on the ileal pouch mucosa.

This study aimed to investigate the effects of the faecal stream and stasis on the mucosa of ileal pouches. Nine patients were followed up. Two pouch biopsy specimens were obtained from each at the time of pouch formation, ileostomy closure, and three, six, and 12 months after operation. None developed pouchitis. Two pouch biopsy specimens each were also obtained from 20 patients (six with pouchitis), whose pouches had been functioning for at least a year and in whom pouch evacuation was assessed by radioisotope labelled artificial stool. Biopsy specimens were assessed for the degree of acute and chronic inflammation, mucin type (high iron diamine-alcian blue stain), a morphometric index of villous atrophy (villous height:total mucosal thickness), and crypt cell proliferation (using the monoclonal antibody Ki67). Mean values from the two biopsy specimens were obtained for each parameter. After three months of pouch function, the scores for acute and chronic inflammation, the degree of sulphomucin, and crypt cell proliferation were significantly higher, and the index of villous atrophy was significantly lower (indicating a greater degree of villous atrophy), than at pouch formation or at ileostomy closure. The values at pouch formation and ileostomy closure were similar. For all parameters, the changes seen at six and 12 months were not significantly different from those at three months. There was no significant correlation between the efficiency of pouch evacuation and any of the mucosal changes. It is concluded that exposure to the faecal stream is necessary for changes to take place in the pouch mucosa, although the amount of stasis, as measured by radioisotopic evacuation studies, seems to be irrelevant. The mucosal changes occur soon after ileostomy closure and then remain stable for at least one year.

Adult↗