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Biomedical subjects

D C Carter

Publications and source records attributed to D C Carter.

At least 91 records · Page 5Linked to original sources
PubMed1991

Injection sclerotherapy for bleeding varices: risk factors and complications.

Risk factors for complications after injection sclerotherapy were studied in 163 patients undergoing 667 treatments for bleeding oesophageal varices. The overall mortality rate was 7 per cent per injection sclerotherapy session; 16 per cent per acute session and 2.4 per cent per elective session. Acute variceal bleeding was controlled by injection sclerotherapy in 91 per cent of patients. Complications occurred after 16 per cent of injection sclerotherapy sessions. Deaths and complications were significantly associated with poor modified Child's grading (P less than 0.001), the first variceal bleed (P less than 0.001), acute injection sclerotherapy (P less than 0.001) and the use of the rigid oesophagoscope (P less than 0.001).

Esophageal and Gastric Varices↗
PubMed1991

Cyclic adenosine 3',5'-monophosphate binding proteins in human colorectal cancer and mucosa.

Cyclic AMP Binding Proteins (cAMP-BP) levels have been measured by means of a competitive binding assay in the cytosols of 50 human colorectal cancers. These levels have been related to those in mucosa both adjacent to and distant from the tumour in the same patients. Cyclic AMP-BP were higher in tumour than in either adjacent (P less than 0.000001) or distant mucosa (P less than 0.00001). Binding of cAMP in adjacent mucosa was lower than that in distant mucosa (P less than 0.0001). There was no significant difference in the level of binding between tumours arising from different sites in the colon and binding was not related to age or sex of the patient. However, binding was higher in Dukes' B than Dukes' C cancers (P less than 0.005). There was also a trend for cAMP binding levels to be higher in moderately differentiated than in poorly differentiated cancers (P = 0.07). Thus cAMP-BP appear to be over-expressed in human colorectal cancers and levels are related to the stage and grade.

Aged↗
PubMed1991

The effect of the somatostatin analogue SMS 201-995 on experimental pancreatic carcinogenesis in the Syrian golden hamster.

Somatostatin analogues have been suggested as possible therapy for human pancreatic cancer. This paper investigates the effect of the somatostatin analogue SMS 201-995 (Sandoz) in the Syrian golden hamster model of nitrosamine-induced pancreatic carcinogenesis. Step-wise increasing doses of i.v. SMS 201-995 suppressed pancreatic juice output from a median basal value of 212 mg/kg body wt/h (Q1:Q3 = 121:334) to a median basal value of 70 mg/kg body wt/h during infusion of 5 micrograms/kg body wt/h of SMS 201-995 (Q1:Q3 = 64:102, P less than 0.05). Chronic s.c. injection of 5 and 10 micrograms/kg body wt SMS 201-995 twice daily for 3 days each week, did not affect pancreatic wet wt or pancreatic total DNA content after 1 or 6 weeks of treatment when compared to controls. The most interesting and unexpected finding in our study was that SMS 201-995 seemed to promote pancreatic carcinogenesis when administered in low dosage. More SMS 201-995 treated animals receiving 5 micrograms/kg body wt developed invasive pancreatic adenocarcinoma than controls after 15 weeks of carcinogen (4/10 animals versus 0/10, P less than 0.05, Fisher's exact test) and pancreatic involvement by tumour was more extensive (17/75 pancreatic blocks affected versus 0/71, P less than 0.001). When carcinoma in situ and microcarcinomata were analysed with invasive lesions, animals injected with 5 micrograms/kg body wt SMS 201-995 were still significantly more affected than controls (33/75 blocks versus 9/71, P less than 0.001). Hamsters injected with the higher SMS 201-995 dose (10 micrograms/kg body wt) did not show any increase in malignancy over the controls. These results suggest that the effect of SMS 201-995 on pancreatic carcinogenesis in the Syrian hamster is complex and varies with dose administered. Further work is required before its use on man can be justified.

Animals↗
PubMed1990

Crystallization of the Fab from a human monoclonal antibody against gp 41 of human immunodeficiency virus type I.

A monoclonal IgG antibody directed against gp 41 from the human immunodeficiency virus (HIV-1) has been crystallized in both intact and Fab forms. Crystals of the intact antibody grow as tetragonal-like prisms too small for conventional X-ray analysis. However, the Fab portion of the antibody produces suitable plate-like crystals which belong to the space group P2(1)2(1)2(1) with unit cell constants of a = 66.5 A, b = 74.3 A and c = 105.3 A. There is one molecule of Fab in the asymmetric unit. The Fab crystals show diffraction to d-spacings less than 3.0 A.

Antibodies, Monoclonal↗
PubMed1990

Preliminary crystallographic examination of a novel fungal lysozyme from Chalaropsis.

The lysozyme from the fungus of the Chalaropsis species has been crystallized. This lysozyme (Mr 22,415) displays no sequence homology with avian, phage, or mammalian lysozymes, however, preliminary studies indicate significant sequence homology with the bacterial lysozyme from Streptomyces. Both enzymes are unusual in possessing beta-1,4-N-acetylmuramidase and beta-1,4-N,6-O-diacetylmuramidase activity. The crystals grow from solutions of ammonium sulfate during growth periods from several months to a year. The space group is P2(1)2(1)2(1) with a = 34.0 A, b = 42.6 A, c = 122.1 A. Preliminary data indicate that there is 1 molecule/asymmetric unit. A complete native data set has been collected to 2.57-A resolution. The crystals are highly ordered and exhibit diffraction patterns to d-spacings less than 1.5 A.

Crystallization↗
PubMed1990

Three-dimensional structure of human erythrocytic purine nucleoside phosphorylase at 3.2 A resolution.

The three-dimensional structure of human erythrocytic purine nucleoside phosphorylase has been determined at 3.2 A resolution using x-ray diffraction data. Intensity data were measured using radiation from the Synchrotron Radiation Source, Daresbury, England, and oscillation film techniques. Phases were determined by using multiple isomorphous replacement methods with four heavy-atom derivatives and were improved using solvent flattening techniques. Purine nucleoside phosphorylase exists in the crystal as a trimer in which subunits are related by a crystallographic 3-fold axis. Each subunit contains an eight-stranded mixed beta-sheet and a five-stranded mixed beta-sheet which join to form a distorted beta-barrel structure. This core beta-structure is flanked by seven alpha-helices in a manner that generates a novel folding pattern. The active site, which was characterized from binding of the substrate analogs 8-iodoguanine and 5'-iodoformycin B, is located near the subunit-subunit boundary within the trimer and involves seven different segments from one subunit and an additional short segment from an adjacent subunit. In the crystal, the phosphate-binding site is probably occupied by a sulfate ion. The specificity of purine nucleoside phosphorylase for guanine, hypoxanthine, and their analogs can be explained on the basis of the arrangement of hydrogen bond donors and acceptors in the active site.

Amino Acid Sequence↗
PubMed1990

Management of gastric variceal haemorrhage.

From March 1979 to April 1988 nine patients with hepatic cirrhosis have presented with acute variceal haemorrhage from gastric varices. Of six patients who underwent emergency laparotomy those with modified Child's grade C (n = 3) died within 30 days of surgery. Six patients have been followed for 2 years or longer. In the three patients who underwent under-running of gastric varices alone, two patients developed oesophageal varices at 3 and 14 months, respectively, and in the third patient gastric varices recurred 3 years after surgery. In the remaining three patients, additional left gastric vein ligation was not associated with recurrence of gastric varices or the development of oesophageal varices.

Adult↗
PubMed1990

Aetiology of pancreatic cancer.

Curative surgery is possible in only a small minority of patients with pancreatic cancer and, to date, responses to chemotherapy and radiotherapy have been disappointing. To make any impact on the incidence of the disease a clearer understanding of its aetiology is required. This review explores present knowledge of the aetiology and epidemiology of pancreatic cancer.

Cholelithiasis↗
PubMed1990

Pancreatic and biliary pressure changes during ERCP.

Injection of contrast is a prerequisite for endoscopic retrograde cholangiopancreatography. Such injection into the biliary and pancreatic duct systems may require considerable force. This paper reports the changes in pressure that result within the duct systems and highlights the significant pressure rise that occurs within the pancreatic duct.

Bile Ducts↗
PubMed1990

Propranolol in the prevention of recurrent variceal hemorrhage in cirrhotic patients. A controlled trial.

A double-blind controlled study of long-acting propranolol in the secondary prevention of variceal hemorrhage was conducted in 81 cirrhotic patients. After the index hemorrhage, all patients were treated with injection sclerotherapy on one occasion to secure hemostasis and then randomized within 72 h to propranolol or placebo therapy which was continued for 2 yr. Study endpoints were severe recurrence of variceal hemorrhage or death. Forty-two patients did not fulfill the entry criteria for the study. Thirty-eight patients received propranolol of whom 18 (47%) had further hemorrhage, 14 died, eight had side-effects (2 withdrawals), and 3 did not complete follow-up. Forty-three patients received placebo of whom 33 (77%) had further hemorrhage, 19 died, 5 had side-effects (2 withdrawals), and 5 failed to complete follow-up. The median time from onset of hemorrhage to starting drug therapy was 6 days for both groups. Life table analysis showed an equivalent incidence of further hemorrhage in both groups over the first 60 days, following which the propranolol group did consistently better than the placebo group. There was a significantly lower incidence of rebleeding in modified Child's C patients receiving propranolol (39%) than those on placebo (90%). No statistically significant effect on mortality was seen. In this study, propranolol reduced the incidence of late recurrence of variceal hemorrhage in patients with cirrhosis.

Double-Blind Method↗
PubMed1990

p53 gene mRNA expression and chromosome 17p allele loss in breast cancer.

p53 messenger RNA expression was examined using a cDNA probe in 76 fresh primary breast tumour specimens, 15 of which came from patients treated with toxoxifen prior to surgery. A 2.8 kb mRNA for p53 was expressed in 43 of the 76 specimens. In 19 tumours the levels were similar to those seen in non-malignant (reduction mammoplasty) breast tissue, but in 24 tumours over-expression of mRNA for p53, approaching that seen in three breast cancer cell lines, was found. The cell lines MCF-7, T-47D and MDA-MB-231 expressed three p53 mRNA species of about 2.8 kb and a forth of 1.6 kb. Increased mRNA expression for p53 correlated (P less than 0.05) with loss of genetic material from the short arm of chromosome 17 as demonstrated by allele loss with the VNTR probe YNZ 22.1. There was also statistically significant correlation between increased p53 mRNA expression and low oestrogen receptor protein content in the tumours (P less than 0.05), but not with other clinical parameters. The findings support the view that p53 is involved in breast tumour biology, and suggest that its role may be complex.

Alleles↗
PubMed1990

Gene expression in oestrogen-dependent human breast cancer xenograft tumours.

Xenograft tumours from an oestrogen-dependent human breast cancer cell line MCF-7 have been established and characterised in thymectomised, irradiated female CBA strain mice. There was evidence for selection in xenografts of a subpopulation of MCF-7 cells with an altered pattern of gene expression as measured by mRNA levels compared with the original cells in vitro. Tumorigenicity increased significantly on repeated animal passage but oestrogen dependence was retained. Following injection of the mice with oestrogen, mitosis was induced in the tumour cells with associated increases in thymidine uptake and percentage of cells in S-phase. In accord with these changes, c-myc and p53 expression were increased and TGF-beta was suppressed. Thereafter the expression of the c-myc and p53 genes fell whilst that of the TGF-beta gene was induced as the oestrogenic-stimulus declined. The oestrogen-regulated mRNA pS2 showed a biphasic response to oestrogen and levels declined as the serum oestrogen fell to undetectable levels. This xenograft system demonstrates that changes in transcription of oncogenes, growth factor and oestrogen-regulated genes can be detected in vivo in response to oestrogen. It thus provides an in vivo model for studies of the biochemical and molecular basis for therapeutic manipulation of hormone-sensitive human breast cancer.

Animals↗
PubMed1990

Prostaglandin E2 production by rat peritoneal macrophages: role of cellular and humoral factors in vivo in transfusion-associated immunosuppression.

The transfusion of blood is associated with long-term immunosuppression, which has been postulated to influence immunosurveillance and cancer cell killing. The mononuclear phagocyte synthesises large quantities of PGE2, and PGE2 has been shown to inhibit the activity of a range of immunocompetent cell types. The role of mononuclear phagocyte PGE2 synthesis in transfusion-associated immunosuppression, and the elements of transfused blood which control this immunosuppression, were investigated using a transfused rat model. A significant increase in macrophage PGE2 synthesis was detected 7 days after transfusion with blood and serum. The storage of blood for 24 h increased the stimulatory activity of transfused blood. The effects of storage and serum on macrophage PGE2 synthesis were greater than effects due to genetic differences between blood donor and recipient, and the serum effects indicated that a major factor activating PGE2-mediated immunosuppression in transfused subjects may be humoral in nature.

Animals↗
PubMed1989

Protein crystal growth in microgravity.

The crystals of most proteins or other biological macromolecules are poorly ordered and diffract to lower resolutions than those observed for most crystals of simple organic and inorganic compounds. Crystallization in the microgravity environment of space may improve crystal quality by eliminating convection effects near growing crystal surfaces. A series of 11 different protein crystal growth experiments was performed on U.S. space shuttle flight STS-26 in September 1988. The microgravity-grown crystals of gamma-interferon D1, porcine elastase, and isocitrate lyase are larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions than the best crystals of these proteins grown on Earth.

Animals↗
PubMed1989

Three-dimensional structure of human serum albumin.

The three-dimensional structure of human serum albumin has been solved at 6.0 angstrom (A) resolution by the method of multiple isomorphous replacement. Crystals were grown from solutions of polyethylene glycol in the infrequently observed space group P42(1)2 (unit cell constants a = b = 186.5 +/- 0.5 A and c = 81.0 +/- 0.5 A) and diffracted x-rays to lattice d-spacings of less than 2.9 A. The electron density maps are of high quality and revealed the structure as a predominantly alpha-helical globin protein in which the course of the polypeptide can be traced. The binding loci of several organic compounds have been determined.

Humans↗