Search PubMed⌕ Search

Biomedical subjects

L W Powell

Publications and source records attributed to L W Powell.

At least 289 records · Page 16Linked to original sources
PubMed1967

Use of diethylenetriamine penta-acetic acid (D.T.P.A.) in the clinical assessment of total body iron stores.

As a quantitative test of iron storage the six-hour urinary excretion of iron was measured after the intravenous infusion of the iron-chelating agent diethylenetriamine penta-acetic acid (D.T.P.A.). The value of this test in determining the presence and magnitude of the total body iron stores was assessed in patients with diseases of iron storage. In patients with idiopathic haemochromatosis and in their first-degree relatives with increased iron stores as measured by hepatic biopsy, the result of the D.T.P.A. test fell progressively as iron stores were reduced by venesection therapy. There was a significant correlation between the result of the D.T.P.A. test and the excess iron storage as measured retrospectively by the effects of venesection therapy, and also between the D.T.P.A. test and the unsaturated iron-binding capacity (U.I.B.C.) in these patients. In patients with excess iron stores due to diseases other than idiopathic haemochromatosis (e.g., alcoholic cirrhosis, haemochromatosis associated with refractory anaemia) the D.T.P.A. test demonstrated the presence of excess iron stores, but the results were very variable and did not correlate closely with the U.I.B.C. or the degree of hepatic haemosiderin deposits. Unexpectedly high results for the D.T.P.A. test were found in some patients with iron-deficiency anaemia.

Adult↗
PubMedDate not supplied

HLA typing in idiopathic hemochromatosis: distinction between homozygotes and heterozygotes with biochemical expression.

In a study of 20 families with idiopathic hemochromatosis, relatives of probands were classified as either homozygous, heterozygous, or normal according to their HLA phenotype. An abnormality in the serum iron concentration, total iron-binding capacity, or serum ferritin concentration was present in all homozygotes and in 25% of heterozygotes. In heterozygotes, the mean total iron-binding capacity was significantly decreased, and the mean hepatic iron concentration was significantly increased compared to normals. However, in contrast to homozygotes, clinical evidence of iron overload was not observed in heterozygotes, and there was no biochemical or histological evidence of liver disease resulting from excessive iron stores. Progressive iron overload did not develop in 44 heterozygotes who were studied for up to 16 yr.

Adolescent↗
PubMedDate not supplied

Value of hepatic iron measurements in early hemochromatosis and determination of the critical iron level associated with fibrosis.

The role of the measurement of hepatic iron in the diagnosis of genetic hemochromatosis was studied, with particular reference to the differentiation of early hemochromatosis from alcoholic siderosis and the critical hepatic iron concentration associated with fibrosis in hemochromatosis. Hepatic iron was measured in 30 homozygous relatives of 17 hemochromatosis probands, 8 heterozygous relatives, 51 patients with alcoholic liver disease and 40 control subjects. Hepatic iron concentrations were greatly increased in the majority of homozygous hemochromatosis subjects, and there was little overlap with the other groups. In the absence of alcoholism, fibrosis or cirrhosis in hemochromatosis was present only with hepatic iron concentrations above a threshold of approximately 400 mumoles per gm (22.3 mg per gm) dry weight. In some heterozygous hemochromatosis subjects and in some alcoholic patients, hepatic iron concentrations were in the range seen in young homozygous subjects. However, an age-related rise in hepatic iron was seen only in hemochromatosis homozygotes, and calculation of an hepatic iron index (hepatic iron/age) resulted in a clear distinction between homozygotes and the other three groups. It is concluded: that chemical measurement of hepatic iron concentration, when corrected for the age of the subject, reliably distinguishes early hemochromatosis from alcoholic siderosis, and, that there appears to be a threshold level of hepatic iron above which there is a high risk of fibrosis.

Adolescent↗
PubMedDate not supplied

CAH or SLE?

Explore the source record for details and available documents.

Fluorescent Antibody Technique↗
PubMedDate not supplied

The prognosis of chronic active hepatitis without cirrhosis in relation to bridging necrosis.

Sixty-nine patients with chronic active hepatitis without cirrhosis were studied to define the prognostic implications of bridging necrosis of various types. There were 19 patients without bridging necrosis compared with 50 patients with bridging necrosis. The two groups did not differ significantly at presentation in age, sex, clinical or laboratory features. In the group without bridging necrosis, no patient died from the disease and none of 13 having a later biopsy developed cirrhosis. In the group with bridging necrosis, one patient died from hepatic failure and 7 of 36 developed cirrhosis (19%). When analyzed statistically, a significant (p less than 0.05) relationship is seen between increasing severity of initial lesion and the subsequent development of cirrhosis. It is concluded that patients with piecemeal necrosis without bridging should not be grouped together with patients with bridging necrosis or cirrhosis when considering management decisions.

Adolescent↗
PubMedDate not supplied

Isolation of a human hepatic ferritin receptor.

A human hepatic ferritin receptor has been isolated from human liver and has been purified using affinity chromatography. An affinity constant of 6.0 x 10(8) moles-1 liter was determined for the ferritin receptor. The molecular weight was estimated to be approximately 53,000 by gel electrophoresis. Binding of ferritin to the receptor coupled to a microparticulate support was specific for human liver ferritin with no binding of rat or porcine ferritin. Binding was unaffected by a 100-fold excess of human transferrin, human asialoorosomucoid and bovine albumin. After treatment of the receptor protein with trypsin, binding was not detected. The human hepatic ferritin receptor may play an important role in the uptake of iron into the hepatocyte in physiological and pathological conditions.

Animals↗
PubMedDate not supplied

Functional roles of the ferritin receptors of human liver, hepatoma, lymphoid and erythroid cells.

Ferritin receptors are present on the membranes of many normal and malignant cells. The binding specificity of these receptors for H and L subunits was examined using recombinant human ferritin homopolymers. At least two different types of ferritin receptors were found, one derived from normal rat, pig, and human liver which shows similar binding of H- and L-ferritin. The second receptor type, specific for the H-chain ferritin, has been identified on membranes of hepatic and other transformed cells, and of normal lymphoblasts and erythroid precursors. These two receptor types may have different metabolic functions: the hepatic receptor acting as a scavenger for circulating ferritin and possibly for iron exchange between hepatocytes and macrophages; the H-ferritin receptor having a regulatory role which is not directly related to iron metabolism. The expression of the H-ferritin receptor is closely related to the activation and proliferation state of the cells. Addition of H-ferritin to the culture medium of cells expressing the H-ferritin receptor resulted in inhibition of cell proliferation and of colony formation.

Animals↗
PubMedDate not supplied

Use of community genetic screening to prevent HFE-associated hereditary haemochromatosis.

HFE-associated hereditary haemochromatosis is a recessive, iron-overload disorder that affects about one in 200 north Europeans and that can be easily prevented. However, genetic screening for this disease is controversial, and so we assessed whether such screening was suitable for communities. Cheek-brush screening for the Cys282Tyr HFE mutation was offered to individuals in the workplace. Outcomes were assessed by questionnaires before and after testing. 11,307 individuals were screened. We recorded no increase in anxiety in individuals who were homozygous for the Cys282Tyr mutation or non-homozygous. Self-reported tiredness before testing was significantly higher in homozygous participants than in non-homozygous participants (chi2 test, p=0.029). Of the 47 homozygous individuals identified, 46 have taken steps to treat or prevent iron accumulation. Population genetic screening for HFE-associated hereditary haemochromatosis can be practicable and acceptable.

Adult↗