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Biomedical subjects

J Powell

Publications and source records attributed to J Powell.

At least 235 records · Page 13Linked to original sources
PubMed1987

Primary gastric lymphoma.

This is a population-based review of 153 cases of primary gastric lymphoma. Sixty-seven (43 per cent) were histologically reviewed using the Kiel classification. There were no significant differences between reviewed and unreviewed cases. Ninety-seven per cent of all cases were of the non-Hodgkin's type. The annual incidence was constant at 1.2 per cent of gastric malignancies. The mean age was 60 years and the male to female ratio 1:8. Presenting symptoms were similar to those of gastric cancer. Twenty-one per cent had a palpable mass but one-third of these were amenable to a potentially curative resection. Some 66 per cent were resectable and 58 per cent had a macroscopic clearance of tumour. TNM stage and absolute tumour size were significant prognostic factors (P less than 0.005 and P less than 0.05 respectively) but the Kiel classification was not. The overall 5 year survival was 24 per cent. Apart from 10 patients whose only anti-tumour treatment was radiotherapy (5 year survival 36.9 per cent) no patient who did not have curative surgery survived 5 years. The 5 year survival for curative resection was 34 per cent and for curative resection plus radiotherapy was 43.5 per cent (45 and 73.4 per cent for the node negative cases respectively). A laparotomy is essential; 'curative' surgery possibly with adjuvant radiotherapy offers the best hope for cure.

Adolescent↗
PubMed1987

Raised serum thyrotrophin in women with peripheral arterial disease.

Women with symptomatic peripheral arterial disease were screened for impaired thyroid function using a sensitive immunoradiometric assay for thyrotrophin (TSH). The arterial disease in the aortotibial segment was documented by an abnormal brachial/ankle pressure index in 80 patients. An age-matched control group of elderly women (n = 30) with a normal pressure index was established. In the control group the mean serum TSH was 1.6 +/- 1.1 milliunits/l, median 1.5 milliunits/l and this established a normal range of 0.2-3.9 milliunits/l. Seven patients (8.8 per cent) were already receiving treatment for myxoedema. In the remaining patients, the overall distribution of serum TSH was skewed to higher levels; the mean was 3.7 milliunits/l, median 2.4 milliunits/l, P less than 0.001 compared with controls and 15 (19 per cent) had a serum TSH greater than 4 milliunits/l, compared with only one (3.3 per cent) of the controls. Therefore 22 patients (28 per cent) had myxoedema or a raised serum TSH. For all subjects with a normal TSH, there was a positive correlation of serum TSH with serum cholesterol, r = 0.68, P less than 0.001. For patients with a raised TSH, there was a continuing, but non-linear, increase of serum cholesterol with TSH. These results suggest that a raised serum TSH may be one of the risk factors for the development of peripheral arterial disease in women, possibly by increasing cholesterol levels.

Aged↗
PubMed1987

Amino acid sequence of rabbit kidney neutral endopeptidase 24.11 (enkephalinase) deduced from a complementary DNA.

Neutral endopeptidase (EC 3.4.24.11) is a major constituent of kidney brush border membranes. It is also present in the brain where it has been shown to be involved in the inactivation of opioid peptides, methionine- and leucine-enkephalins. For this reason this enzyme is often called 'enkephalinase'. In order to characterize the primary structure of the enzyme, oligonucleotide probes were designed from partial amino acid sequences and used to isolate clones from kidney cDNA libraries. Sequencing of the cDNA inserts revealed the complete primary structure of the enzyme. Neutral endopeptidase consists of 750 amino acids. It contains a short N-terminal cytoplasmic domain (27 amino acids), a single membrane-spanning segment (23 amino acids) and an extracellular domain that comprises most of the protein mass. The comparison of the primary structure of neutral endopeptidase with that of thermolysin, a bacterial Zn-metallopeptidase, indicates that most of the amino acid residues involved in Zn coordination and catalytic activity in thermolysin are found within highly honmologous sequences in neutral endopeptidase.

Amino Acid Sequence↗
PubMed1987

Coated intraocular lenses.

We found that an intraocular lens with a bonded coating of sodium hyaluronate caused less cell damage than an uncoated lens. We also found that an intraocular lens bonded with sodium hyaluronate will provide not only better adherence to viscoelastic materials and endothelial protection, but also may allow for better manipulation of the lens intraocularly. This is the first report of a sodium hyaluronate-coated intraocular lens used to prevent cell damage.

Animals↗
PubMed1986

The primary structure of bovine chromogranin A: a representative of a class of acidic secretory proteins common to a variety of peptidergic cells.

We have determined the primary structure of bovine chromogranin A as a first step in the elucidation of the function of this widespread protein. After oligonucleotide screening of a cDNA library of bovine adrenal medulla, a clone (insert length 1.9 kb) containing the entire coding region for chromogranin A was isolated and sequenced. The authenticity of the sequence was verified by comparison with N-terminal, several internal, and C-terminal amino acid sequences as well as the amino acid composition of chromogranin A. The cDNA clone hybridized to an mRNA of 2.1 kb and, after in vitro transcription-translation, yielded a polypeptide with a similar electrophoretic mobility in SDS gels to chromogranin A. The polypeptide chain of chromogranin A comprises 431 amino acid residues, corresponding to an unmodified protein of 48 kd, and is preceded by a cleaved signal peptide of 18 amino acid residues. Interesting features of the chromogranin A structure include repeated clusters of glutamic acid residues, the occurrence of eight potential dibasic cleavage sites, six of which are located in the C-terminal domain, and the presence, in the N-terminal domain, of -Arg-Gly-Asp- (RGD), a three amino acid sequence involved in the binding of several constitutively secreted proteins to cell membranes.

Adrenal Medulla↗
PubMed1985

Serum testosterone concentrations in the evaluation of androgen-producing tumors.

During a 5-year study period 18 women with a serum testosterone concentrations of greater than 2 ng/ml were evaluated for a possible androgen-producing tumor. All subjects were hirsute and had menstrual irregularities, with the exception of one postmenopausal woman. The majority of the women were obese and 72% were greater than 50% over ideal body weight. Only two of 11 women undergoing operative and histologic evaluation of the ovaries were found to have an androgen-producing neoplasm. Seven additional women with serum testosterone concentration of greater than 2 ng/ml have been followed for over 1 year with no additional evidence of an androgen-producing neoplasm. The poor predictive value of a serum concentration of greater than 2 ng/ml in identification of an androgen-producing neoplasm is partially explained by the apparent prevalence of high testosterone concentrations in chronically anovulatory, hyperandrogenic obese women and by the large coefficient of variation observed in this study when analyzing testosterone concentrations were analyzed over an 8-hour interval (range, 3% to 42%). In the absence of an adnexal mass or rapidly progressive virilization, it is suggested that the use of venography or operative exploration to diagnose an androgen-producing neoplasm be reserved for women with a mean testosterone concentration derived from three daily samples that is at least 2.5 times greater than the upper range of normal in the given laboratory.

Androgens↗
PubMed1985

Platelet-derived growth factor enhances in vitro erythropoiesis via stimulation of mesenchymal cells.

The growth of erythroid colonies (from erythroid colony-forming cells) and erythroid bursts (from burst-forming cells [BFU-E]) is enhanced in the presence of serum as compared with plasma. A significant proportion of the enhanced growth is due to the platelet release product, platelet-derived growth factor (PDGF). Colony growth in cultures of whole marrow cells in platelet-poor plasma-derived serum (PDS) and erythropoietin was enhanced in a dose-dependent fashion by increasing concentrations of purified human PDGF with optimal enhancement at 12.5 ng/ml. However, no effect of platelet-release products or PDGF was observed on nonadherent human marrow cells or peripheral blood BFU-E, suggesting that an accessory cell population was required for the effect of PDGF on hematopoietic progenitors. In a two-layer culture system, pure populations of fibroblasts or smooth muscle cells, known to be present in the marrow microenvironment, restored the response of nonadherent marrow cells in the overlayer to PDGF and also conferred responsiveness to peripheral blood BFU-E. Endothelial cells in the two-layer culture system and macrophages, in contrast, lacked the ability to restore the enhancing effect of PDGF. Because other platelet-release mitogenic products are also found in serum, a monospecific anti-PDGF IgG preparation was added to cultures grown in platelet rich plasma-derived serum. Only partial reduction in colony and burst growth was seen, suggesting that other platelet-release products were acting in this system. These results demonstrate that PDGF enhancement of human hematopoietic progenitor cell growth requires mesenchymal cells, and provide an example and mechanism by which growth factors may influence hematopoietic progenitors via cells of the marrow microenvironment.

Bone Marrow↗
PubMed1984

Clinicopathological staging of gastric cancer.

13 175 patients with gastric carcinomas have been staged with reference to the TNM staging system. This has confirmed the poor overall prognosis (5.5 per cent and 3.8 per cent age-adjusted survival rates at 5 and 10 years respectively). However, it has demonstrated the significant survival associated with the treatment of Stage I disease (70.0 per cent at 5 years and 63.2 per cent at 10 years). This study demonstrates that 72.9 per cent of cases are unresected and that interpretation of resectability rates must be related to the population base of the study.

Humans↗
PubMed1984

Incidence and prognosis of N4 node involvement in gastric cancer.

We have undertaken a prospective study of the frequency and prognosis associated with N4 node metastases in gastric cancer in 136 patients referred for surgical treatment between 1976 and 1983. N4 node metastases (pre-aortic or hepatic hilar nodes) were present in 20 of 31 patients who had a laparotomy without resection (64 per cent), in 2 of 8 patients who had a 'palliative' resection in the presence of distant metastases (25 per cent) and, in 19 of 85 patients who had a 'curative' resection (22 per cent). The median survival in patients having a 'curative' resection with N4 nodes was 4.5 months which was only marginally longer than in patients having a 'palliative' resection (median survival 3 months). In view of these findings and since immediate imprint cytology can be used to detect nodal metastases at operation, involvement of N4 nodes might be a contra-indication to extensive gastric resection in non-obstructing gastric cancer.

Humans↗