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Biomedical subjects

H Greenwood

Publications and source records attributed to H Greenwood.

15 recordsLinked to original sources
PubMed1996

c-erb B-2 and p53 expression in breast cancer fine needle aspirates.

The aim of this study was to co-evaluate c-erb B-2 and p53 protein expression in breast cancer fine needle aspirates (FNA) and to compare this with histological variables and the immunohistochemical phenotype of the tumours. Furthermore, we assessed the relationship of c-erb B-2 and p53 immunocytochemical expression to tumour prognostic factors. We examined 124 breast cancer FNAs and 79 matched surgical specimens using the avidin-biotin complex (ABC) and the alkaline phosphatase immunocytochemical techniques. C-erb B-2 immunopositivity was detected in 37.9% of the FNAs, while 31.7% were positive for p53. A statistically significant correlation was observed between p53 negativity and absence of c-erb B-2 immunostaining in the FNAs (P = 0.0007). Smears from infiltrating ductal carcinomas tended to be more frequently positive for p53 (36.7%) than those from lobular carcinomas (11.7%) (P = 0.054). In matched tumour tissues, c-erb B-2 was positive in 16.7% and p53 in 19% of cases. The immunocytochemical results for both c-erb B-2 and p53 were significantly correlated with the immunohistochemical results. There was no correlation between c-erb B-2 and p53 immunostaining, in both FNAs and tissues, and patients menopausal status, tumour size, grade and lymph node status.

Adult↗
PubMed1991

A comparison of the pharmacokinetic properties of streptokinase and anistreplase in acute myocardial infarction.

1. The pharmacokinetics of streptokinase (SK) and anistreplase in conventional dosage regimens of 1.5 x 10(6) i.u. of SK infused over 60 min and 30 units of anistreplase over 5 min were studied in 24 consecutive patients presenting with acute myocardial infarction, using a functional bioassay to assess concentrations. 2. The two agents were found to have similar volumes of distribution (5.68 and 5.90 l), but SK was cleared significantly more rapidly than anistreplase, resulting in a shorter terminal phase half-life (0.61 vs 1.16 h) and a shorter mean residence time (0.76 vs 1.55 h).

Aged↗
PubMed1987

Calcium- and cyclic AMP-dependent chloride secretion in human colonic epithelia.

Three stable epithelial cell lines (HCA-7, HCA-7-Col 1 and HCA-7-Col 3) all derived from the same human adenocarcinoma have been cultured on collagen-coated Millipore filters. These epithelial monolayers have been used to record short circuit current (SCC) in response to of secretagogues. Similar monolayers, but grown on plastic dishes, were used for measurements of tissue cyclic AMP. Lysylbradykinin, applied to either side of the monolayers, increased SCC in HCA-7 cells but had little effect on the other two lines. The responses showed rapid desensitization, which could be prevented by cooling to 4 degrees C. Responses to kinin were not significantly attenuated by piroxicam, an inhibitor of cyclo-oxygenase. Other secretagogues, vasoactive intestinal polypeptide (VIP) and carbachol also increased SCC in monolayers. The responses to VIP were greatest in HCA-7-Col 1 monolayers while responses were virtually absent in HCA-7-Col 3. A similar profile was seen with carbachol except that responses of HCA-7 and HCA-7-Col 1 monolayers were more equal. With one exception the responses to VIP and carbachol showed sidedness, acting only from the basolateral side. The effects of the secretagogues were inhibited by piretanide, a loop diuretic, applied basolaterally. It is presumed that SCC responses represent electrogenic chloride secretion. Treatment with forskolin increased SCC in HCA-7 and HCA-7-Col 1 monolayers with little effect in HCA-7-Col 3. Nevertheless cyclic AMP levels were elevated most in HCA-7-Col 3 and least in HCA-7-Col 1 monolayers, in reciprocal relationship to the functional response. A23187 increased SCC when applied to HCA-7 and HCA-7-Col 3 monolayers with little effect on HCA-7-Col 1. The differential responses of the three human cell lines provide unique opportunities to discover the functional responsibilities of entities involved in the chloride secretory process. HCA-7-Col 3 cells which generate high levels of cyclic AMP in response to forskolin but which fail to show a substantial chloride secretory response may be a useful model of some disease conditions.

Calcimycin↗
PubMed1983

Relationship between myocardial uptake and actions in heart failure of methyldigoxin.

1 Problems have been encountered in recent years in confirming useful benefit to patients with heart failure and sinus rhythm from acute exposure to digitalis glycosides, though effectiveness of these preparations upon cardiac contractile performance is indisputable. Undesired effects such as those upon systemic vascular resistance have been invoked to explain this. 2 Detailed haemodynamic responses have been studied by cardiac catheterisation in nine such patients for 30 min after intravenous methyldigoxin infusion. Myocardial glycoside uptake was simultaneously assessed. 3 Methyldigoxin uptake by the heart was rapid, passing its peak within 20 min, and was followed by substantial elution. 4 A small progressive and significant increase in cardiac output was observed, though left ventricular filling pressures were not significantly reduced after methyldigoxin. Cardiac contractile function as assessed by left ventricular maximum dP/dt, measured in six patients, showed consistent improvement.

Cardiac Catheterization↗
PubMed1978

Comparison of digoxin and medigoxin in normal subjects.

1 The properties of a recently introduced digitalis glycoside, 4-beta-methyl digoxin (medigoxin) were compared to those of a standard digoxin preparation. Using a radioimmunoassay (RIA) technique, serial plasma levels were recorded for 8 h following a single oral dose in five fasting volunteer subjects, and urinary glycoside elimination was measured for 4 consecutive days after dosage by use of a modification of the RIA method. 2 It was found that this RIA was suitable for plasma level measurement of both digoxin and midigoxin by reference to appropriate standard curves. Comparison of the plasma level profiles of these two drugs showed that medigoxin was very rapidly absorbed with peak levels occurring within 15--30 min, while digoxin produced peak levels after 45--75 min. The area under the plasma level-time curve produced by medigoxin was also consistently greater than that produced by digoxin, even though the medigoxin dose used was smaller. Quantitative comparison of these areas after adjustment to compensate for differing doses showed that medigoxin is considerably more biologically available than digoxin under study conditions (ratio 1.6 +/- 0.25:1), and comparison of quantitative urinary elimination suggested that medigoxin is eliminated in the urine to a lesser extent than digoxin and therefore it undergoes more metabolism and/or hepato-biliary elimination.

Adult↗
PubMed1977

Development of a highly sensitive radioimmunoassay for digoxin and its application in pediatric practice.

The sensitivity of two established routine digoxin radioimmunoassay methods has been increased to enable the provision of a rapid and relatively atraumatic inpatient and outpatient service for neonates and small children, using capillary blood samples obtained by heel-prick. The methods employ 125I- or 3H-labelled digoxin, a rabbit antiserum raised against a digoxin: bovine serum albumin conjugate and only 10 or 25 microliter of plasma as the sample. The results obtained using these highly sensitive assays correlate closely with those found using conventional assays, requiring larger sample volumes. An apparent difference in sensitivity to digoxin has been demonstrated between infants and children more than 1 yr old. Thus infants appear to tolerate plateau phase plasma levels (mean value for non toxic infants 2.6 +/- 1.8 ng/ml) that in older children or adults would be associated with digoxin toxicity.

Binding Sites, Antibody↗
PubMed1977

Radioimmunoassay for digoxin with a fully automated continuous-flow system.

We describe a fully automated continuous-flow radioimmunoassay for digoxin with use of a Technicon AutoAnalyzer system. It makes use of antibodies linked to magnetizable particles; a magnet separates the bound and free fractions. The precise dispensing of reagents by the AutoAnalyzer system permits a small incubation volume (about 160 microliter) and the reproducible timing enables non-equilibrium conditions to be used. Thus a single sample is assayed in 15 min, with a sample throughput of 30/h. The standard curve ranges from 0.5 to 8.0 microgram/liter and is most precise between 1 and 3 microgram/liter, the between-assay coefficient of variation being less than 3%. There is no significant carryover between samples of high and low concentration, and results by the method correlate closely (r = 0.969) with those by an established manual assay in which charcoal separation is used.

Antibody Specificity↗
PubMed1975

The measurement of urinary digoxin and dihydrodigoxin by radioimmunoassay and by mass spectroscopy.

A radioimmunoassay for urinary digoxin is described which includes an initial solvent extraction to remove factors in urine which cause non-specific interference in the assay. The recoveries obtained using different solvents are compared and the non-specific factors influencing the assay investigated further. These effects were overcome by the use of a small urine volume (10 mul) in a direct, unextracted, urine assay and the results obtained correlated closely with those from the assay using prior extraction (r=0.99). No false positive results were obtained with unextracted urine samples from hospitalised patients not receiving digoxin. The specificity was also determined with regard to the natural steroids, spironolactone and the metabolites of digoxin including dihydrodigoxin. The metabolite dihydrodigoxin, with a saturated lactone ring, was not detected whereas the mono-, and bis-digitoxo-sides and digoxigenin metabolites did cross react in the assay. It was not possible to separate dihydrodigoxin and digoxin by thin-layer chromatography or solvent extraction due to their similar structures, however, mass spectroscopy was successful in this respect and was employed to obtain the ratio of dihydrodigoxin to digoxin in extracted urine samples. Levels of urinary digoxin excreted by patients maintained on different oral doses of the drug were measured. The percentage excreted in the urine as digoxin correlated closely with the oral dose (r = 0.96) but was found to be lower than that reported in most previous studies. Mass spectroscopy measurements showed that an average of 16.4% (range 12.2-19.7%) of the total oral dose was excreted as dihydrodigoxin in the urine of nine patients investigated.

Animals↗
PubMed1974

A rapid, simple assay for digoxin.

An extremely rapid radioimmunoassay for digoxin is described which is precise over the range of concentrations required to determine whether, or not, a patient has digoxin toxicity. The assay is based on the use of (125)-iodine-labelled digoxin and of a gel equilibration technique for the separation of antibody-bound and free digoxin. The results obtained compare closely with those by a conventional radioimmunoassay and the technique is sufficiently simple to enable its performance by relatively inexperienced laboratory staff.

Binding Sites, Antibody↗