Search PubMed⌕ Search

Biomedical subjects

M De Luca

Publications and source records attributed to M De Luca.

At least 163 records · Page 9Linked to original sources
PubMed1987

TSH receptor structure.

When solubilized, radiolabelled membrane preparations from FRTL-5 rat thyroid cells are applied to TSH affinity columns, two separate peaks of protein can be eluted by high salts/high pH and low pH buffers, respectively. Immunoprecipitation with monoclonal antibodies to the TSH receptor shows that both peaks contain proteins related to the TSH receptor. If extracts were from cells grown without TSH, one peak has a approximately 300 K and the other a approximately 70 K protein the 70 K protein can be derived from the purified 300 K protein in vitro. A 50 and 20 K protein can be derived from the 70 K protein. If extracts are from cells grown with TSH, the peaks contain a multiplicity of additional immuno-precipitable bands of approximately 200, 175, 130, 90, 50, 20 K etc. These bands are shown to result from the ability of TSH to increase the synthesis (3-4-fold) and degradation (2-3-fold) of the 300 and 70 K proteins. The 300/70 K protein fractions are reactive with monoclonal autoimmune thyroid stimulating antibodies and contain a specific disialo ganglioside. The ganglioside migrates near GM2, i.e., like a lower order ganglioside, and contains fucose. In translation experiments, the monoclonal antibodies to the TSH receptor identify a single mRNA component which produces a protein of approximately 220 K. This protein is not present in thyroid cells which have no functional TSH receptor and which cannot be surface labelled with monoclonal antibodies to the TSH receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

A pilot study of the pharmacokinetics and triglyceride lowering activity of acipimox in dialyzed uremic patients.

The pharmacokinetics of acipimox was studied in 6 dialyzed uremic patients given single oral doses of 50 mg. Acipimox was not significantly eliminated outside dialysis, whereas during dialysis it was efficiently cleared with plasma, t 1/2 is about 2.6 hours. Accordingly, a dosage schedule of 50 mg or 100 mg of acipimox after each dialysis session was selected for a second, 4-week study in 14 uremic patients with hypertriglyceridemia. Acipimox plasma levels, monitored during the study, proved in agreement with those expected on a theoretical pharmacokinetic basis. A clear-cut reduction of serum triglyceride levels was also achieved.

Adult↗
PubMed1985

Radionuclear determination of glomerular filtration rate and renal plasma flow to detect early decrease of renal function in insulin dependent diabetes.

To evaluate the role of renal haemodynamic factors in the pathophysiology of diabetic nephropathy, we determined by radionuclear techniques glomerular filtration rate (GFR) and renal plasma flow (RPF) in 18 patients affected by insulin dependent diabetes mellitus (IDDM) in good metabolic control, with normal blood pressure and plasma creatinine. GFR and RPF measured in the same patients after ten months correlated with proteinuria and duration of diabetes. Our finding of a significant correlation between the decline of RPF and duration of diabetes may support the haemodynamic hypothesis of progression of diabetic nephropathy.

Adolescent↗
PubMed1984

Human undifferentiated thyroid carcinoma synthesizes and secretes 19S thyroglobulin.

Thyroglobulin (Tg) biosynthesis and secretion have been studied in one case of undifferentiated small spindle cell human thyroid carcinoma. From tumor tissue were extracted 32 mg of soluble proteins per gram of wet tissue, compared with 54 mg from control gland; after ammonium sulfate fractionation, density gradient centrifugation, and immunoprecipitation, 1.3 mg of Tg per gram of wet tissue, compared with 31.2 mg from control, were purified. By incubating in vitro up to 3 hours tumor slices with tritiated leucine, galactose, and 125I, the rate of incorporation of leucine and galactose increased with time in tumor tissue. However 125I incorporation into soluble proteins from tumor, at 3 hours of incubation, was only 1.7% of control value. By density gradient centrifugation of labeled soluble proteins a well-separated component sedimenting in the 19S peak was identified. No radioiodine was detected in the 19S fraction which showed the immunoreactive properties of 19S and was poor in 127I and sialic acid. In the incubation medium of tumor were secreted 0.4 mg of 19S Tg per gram of wet tissue compared with 48 mg of tissue in the control gland. Thus the undifferentiated thyroid carcinoma synthesizes a protein with the physiochemical and immunologic properties of 19S Tg. The undifferentiation of thyroid cells does not affect the biochemical steps involved in the synthesis of Tg.

Aged↗
PubMed1983

Coimmobilized multienzymes: an in vitro model for cellular processes.

Two different systems of multienzymes have been coimmobilized onto Sepharose and shown to be catalytically active. The first system consists of the five enzymes that catalyze the conversion of glucose 1-phosphate to 1,3-diphosphoglycerate along with the bacterial enzymes which are used to monitor NADH production by light emission. The NADH:FMN oxidoreductase-luciferase enzymes act to "pull" the reactions by continually oxidizing the NADH formed. The second system consisted of the 11 enzymes necessary for the conversion of glucose to alcohol and the bacterial enzymes. In the presence of excess glucose this immobilized system was able to produce 4068 nmol of alcohol per gram of Sepharose-enzymes in 4 h. Using the same system, if 3-phosphoglycerate was used as the substrate, 6552 nmol of alcohol were formed. These multienzyme immobilized systems are models that are uniquely suited for comparative studies of metabolic processes that occur in intact cells.

Animals↗
PubMed1983

Specificity of thyroglobulin interactions with thyroid cells and membranes.

Homologous species specificity is demonstrated with bovine and human thyroglobulin in which the two terminal sugars of the B carbohydrate chain, sialic acid and galactose have been removed by enzymatic hydrolysis. The species specificity is demonstrated by measuring the ability of the deglycosylated thyroglobulin derivatives to inhibit thyrotropin-induced increases in cAMP in human, rat and bovine thyroid cells in culture. Thus human-human or bovine-bovine interactions have higher activity coefficients by at least an order of magnitude than their heterologous counterparts. The homologous interactions are confirmed in binding studies and shown to be associated with negligible degradation of the bound ligand over a 24 hour period.

Animals↗
PubMed1983

Automated bioluminescent assays for NADH, glucose 6-phosphate, primary bile acids, and ATP.

An automated flow system for the bioluminescent assay of various metabolites have been developed. The enzymes used in the assays have been coimmobilized onto Sepharose and packed into small flow cells. Assays for NADH, glucose 6-phosphate, and primary bile acids utilize the bacterial NADH:FMN oxidoreductase/luciferase and either glucose-6-phosphate dehydrogenase or 7 alpha-hydroxysteroid dehydrogenase. ATP assays were performed using immobilized firefly luciferase. In general, the lower limit of detection of the metabolites was at the picomole level, and light intensity was proportional to the substrate concentration from several picomoles to several hundred picomoles. The reproducibility was good with coefficient of variations in the range of 2-5%. The carryover was less than 5% and 30 samples per hour could be assayed. The flow cells were reusable for up to 700 consecutive assays. The major factor limiting their continued use was bacterial contamination of the Sepharose. The results obtained for serum primary bile acids using the bioluminescent assay wer in good agreement with independent measurements on the same samples using gas-liquid chromatography. The immobilized firefly luciferase system was successfully used to measure high levels of bacteria in urine specimens.

Adenosine Triphosphate↗
PubMed1983

Specific incorporation of penicillamine into the epidermis of mice: an autoradiographic study.

[3H]-D-penicillamine was injected intra-peritoneally in mice. The highest concentration of the drug was found in the skin, particularly in the epidermis, and a well-defined kinetic sequence of appearance in the epidermis was shown. This finding is consistent with the hypothesis that penicillamine, by virtue of its chemical similarity to cysteine, can replace the latter during keratogenesis by a competition phenomenon, which could provoke acantholytic splitting both biochemically and immunologically.

Animals↗
PubMed1982

[Radioimmunologic determination of circulating parathyroid hormone in patients with primary and secondary hyperparathyroidism].

A radioimmunological evaluation was made of plasma parathormone (PTH), using an antibody against the C-terminal fraction, in 14 subjects with primary parahyperthyroidism, and in 19 anuric subjects with secondary forms on three-weekly dialysis. In all cases, values were significantly higher (p less than 0.01) than in a group of normal controls. In secondary forms, the same significance was also apparent on comparison with primary forms, probably due to an absence of renal clearance of the hormone.

Adult↗