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H Pertoft

Publications and source records attributed to H Pertoft.

At least 55 records · Page 3Linked to original sources
PubMed1982

Regulation of parathyroid hormone release in primary and secondary hyperparathyroidism - studies in vivo and in vitro.

The effects of calcium on parathyroid hormone (PTH) release were studied in vivo and in vitro in primary hyperparathyroidism (HPT) and in vitro in secondary HPT. In vivo the serum PTH was clearly reduced by intravenous calcium infusion in all the examined patients with primary HPT caused by adenoma. In vitro the release of PTH from dispersed parathyroid cells was likewise suppressed by raising the calcium concentrations in the incubation media, though in all cases a basal release of PTH still persisted even at high calcium concentrations. The degree of suppressibility in vitro varied, but in both primary HPT with adenoma and in secondary HPT it was inversely related to the patients' serum calcium values. These results suggest that the secretion of PTH in patients with primary and secondary HPT is not autonomous either in vivo or in vitro. Furthermore, the non-suppressible basal release of PTH indicates that a major cause for the increased secretion of PTH is the increased number of parenchymal cells. However, the degree of suppressibility of the individual cells rather than the absolute number of cells, seems to be of great importance for the individual serum calcium values in HPT.

Adenoma↗
PubMed1981

Plasma clearance, tissue distribution and metabolism of hyaluronic acid injected intravenously in the rabbit.

The plasma clearance, tissue distribution and metabolism of hyaluronic acid were studied with a high average molecular weight [3H]acetyl-labelled hyaluronic acid synthesized in synovial cell cultures. After intravenous injection in the rabbit the label disappeared from the plasma with a half-life of 2.5--4.5 min, which corresponds to a normal hyaluronic acid clearance of approx. 10 mg/day per kg body weight. Injection of unlabelled hyaluronic acid 15 min after the tracer failed to reverse its absorption. Clearance of labelled polymer was retarded by prior injection of excess unlabelled hyaluronic acid. The maximum clearance capacity was estimated in these circumstances to be about 30 mg/day per kg body wt. The injected material was concentrated in the liver and spleen. As much as 88% of the label was absorbed by the liver, where it was found almost entirely in non-parenchymal cells. Degradation was rapid and complete, since volatile material, presumably 3H2O, appeared in the plasma within 20 min. Undegraded [3H]hyaluronic acid, small labelled residues and 3H2O were detected in the liver, but there was little evidence of intermediate oligosaccharides. No metabolite except 3H2O was recognized in plasma or urine. Two-thirds of the radioactivity was retained in the body water 24 h later, and small amounts were found in liver lipids. Radioactivity did not decline in the spleen as rapidly as in the liver. The upper molecular weight limit for renal excretion was about 25 000. Renal excretion played a negligible part in clearance. It is concluded that hyaluronic acid is removed from the plasma and degraded quickly by an efficient extrarenal system with a high reserve capacity, sited mainly in the liver.

Animals↗
PubMed1981

A two-step procedure for the purificaton of hepatitis B surface antigen (HBsAg).

Hepatitis B surface antigen (HBsAg) was purified by a simple, rapid, two-step procedure comprising chromatography on dextran sulfate-Sepharose 4B, followed by preparative rate zonal centrifugation on a sucrose gradient. A 230-fold purification of HBsAg was achieved with a yield of about 80%.

Centrifugation, Density Gradient↗
PubMed1981

The parenchymal cell mass in normal human parathyroid glands.

The parenchymal cell mass in parathyroid glands from 368 autopsy cases without apparent parathyroid or kidney disease was investigated. By measuring the glandular density with a density gradient technique and the glandular weight, the parenchymal to fat cell ratio and the weight of the parenchymal cell mass could be determined. The mean parathyroid parenchymal cell weight was calculated to be 22 mg and the maximal normal parenchymal cell weight 39 mg. The glandular weight was evidently dependent on the body constitution, as the fat tissue content of the glands was related to the amount of fat tissue in the body as a whole. The parenchymal cell weight was much less variable. Also, the amount of fat tissue in the parathyroid glands was positively correlated to the size of glands. Thus, the amount of fat cells within parathyroid glands seems less adequate as a histological criterion and the parenchymal cell weight should be of greater value in the histological diagnosis that the weight of the whole gland. The age-and-sex-related variations of the parenchymal cell mass were slight and therefore a value of 39 mg may be considered an appropriate upper limit of the weight of this mass in parathyroid glands of adult persons.

Adipose Tissue↗
PubMed1980

Separation of human monocytes on density gradients of Percoll.

Monocytes from human blood have been isolated by centrifugation in Percoll. A one-step procedure has been designed to isolate the cells from 7 ml of blood. when 5% of the white blood cells are assumed to be monocytes, an estimated average yield of 100% and a purity of 20% is achieved. The contaminating cells are almost exclusively lymphocytes. By a two-step procedure the monocytes can be obtained 90% pure with an approximate yield of 35%. The cells can be used for tissue culture without washing and they display the usual properties of mononuclear phagocytes in vitro.

Blood Coagulation↗
PubMed1980

Estimation of the parathyroid parenchymal cell mass by density gradients.

The density of parathyroid glands was estimated by a density gradient technique. Glandular density was found to be closely related to the parenchymal cell content as estimated with an image-analyzing computer in serial sections. The density gradient technique can therefore be used to determine the relative parenchymal content of parathyroid glands. The density gradient measurements are rapid and reproducible and constitute a suitable method for determining the parathyroid parenchymal cell mass. The convenience of the technique suggests that it should be very useful for intraoperative diagnosis.

Analysis of Variance↗
PubMed1979

Uptake and degradation of mast-cell granules by mouse peritoneal macrophages.

35S-labelled mast-cell granules isolated from mouse mastocytomas were added to mouse macrophages in vitro. The granules were avidly phagocytosed, and subsequently the radioactivity was released to the medium as inorganic [35S]sulphate. After pulse-labelling, a total of about 80% of the cell-associated radioactivity was thus released in the course of 24 h, indicating an extensive breakdown of the sulphated polysaccharides, mainly heparin, present in the granules. The uptake of the mast-cell granules caused pronounced, but reversible, spreading of the macrophages.

Animals↗
PubMed1979

Density determinations of human parathyroid glands by density gradients.

The densities of human parathyroid glands were measured in density gradient columns of various media. Percoll (an aqueous colloidal solution of polyvinylpyrrolidone-coated silica), equilibrated to 300 mOsm with sodium chloride, was found to be the ideal gradient medium for density measurements of tissues with a density greater than 1.0 g/ml. which includes most parathyroid glands. The densities of the glands varied between 0.96 and 1.06 g/ml. Density measurements in gradients of Percoll were simple and reproducible and were made with an accuracy of approximately 0.001 g/ml. In other gradient media (aqueous solutions of sucrose and Ficoll, and organic solvents) there was a drift in density caused by osmotic or lipid-solving effects of the media. For measurements of densities less than 1.0 g/ml no ideal gradient medium was found, but a silicon oil or carbon tetrachloride/kerosone gradient could be used with somewhat reduced accuracy. It is concluded that the density gradient technique with the use of Percoll is potentially useful as a complement to routine histopathological parathyroid diagnosis, as glandular density is a good indicator of the relative proportions of parenchymal and fat tissue.

Adipose Tissue↗
PubMed1978

Heterogeneity of lysosomes originating from rat liver parenchymal cells. Metabolic relationship of subpopulations separated by density-gradient centrifugation.

1. A crude lysosomal fraction obtained by differential centrifugation of a rat liver homogenate was subjected to zonal centrifugation in iso-osmotic self-generating gradients composed of modified colloidal silica (Percoll). Analysis of relevant marker-enzyme activities shows a continuous band of considerably purified lysosomal particles in the density range 1.04--1.11 g/ml. 2. A relationship between age and buoyant density of the parenchymal lysosomal subpopulations is indicated by the distribution of 125I-labelled asialoglycoproteins in the heterogeneous lysosomes during the catabolism of the glycoprotein. The labelled asialoglycoprotein first appeared in lysosomal particles of low density, which with time progressively acquired a higher density. Furthermore, 30 min after administration the 125I-labelled asialocaeruloplasmin recovered in the light lysosomes was less degraded than the material recovered in the heavy lysosomes. 3. A lysosomal enzyme (arylsulphatase) was found to possess considerably higher isoelectric points in the heavy lysosomes than in the light lysosomes, which is consistent with a relationship between age and density of the lysosomes.

Animals↗
PubMed1978

Isolation and characterization of cells from rat adipose tissue developing into adipocytes.

To identify cells developing into adipocytes by accumulation of triglyceride, rat epididymal fat pad cells from small rats were exposed to (3)H-labeled chylomicron fatty acids in vivo and then liberated with collagenase. Tissue remnants were removed by filtration and mature fat cells by flotation. Aggregating cells were then removed by filtration through a 25- micro m nylon screen. Further purification of cells labeled in vivo was obtained by removing floating cells from those adhering to the bottom of a culture dish. The adhering cells multiplied to a confluent monolayer when cultured in Medium 199 containing serum, glucose, insulin, and a triglyceride emulsion. The cells then gradually enlarged due to granulation of the cytoplasm by a lipid-staining material. After about 2 weeks these granules had coalesced forming mature adipocytes of typical signet-ring appearance. Free adipocytes could then be recovered from the cultures by collagenase treatment. After about 2 weeks of culture these cells had the same size (about 30 micro m) as adipocytes recovered in the original collagenase preparation of the rat epididymal fat pad. They contained triglyceride lipase activity and incorporated glucose into triglycerides to the same extent as cells developed in vivo but had higher lipoprotein lipase activity. In vitro, heparin in a low concentration, prostaglandin E(1), isobutylmethylxanthine, and cholera toxin markedly promoted the development of these cells into adipocytes. This could be shown to occur almost completely indicating that this fraction of cells was homogeneous and consisted of cells with the capacity to form adipocytes. The duplication time was about 2 days and did not change with subculturing. Preadipocytes could be obtained by density gradient centrifugation, isolating triglyceride-containing cells either directly from the pad or after 3 days in culture. All of these cells developed into adipocytes as described above but did not multiply as readily. It was concluded that cells from the epididymal fat pad from small rats can be isolated in a homogenous fraction that develops in culture into cells of identical morphology and function as adipocytes formed in vivo. The differentiation of these cells into adipocytes may be manipulated in vitro.

Adipose Tissue↗
PubMed1977

Structure and metabolism of rat liver heparan sulphate.

Rat liver cells grown in primary cultures in the presence of [(35)S]sulphate synthesize a labelled heparan sulphate-like glycosaminoglycan. The characterization of the polysaccharide as heparan sulphate is based on its resistance to digestion with chondroitinase ABC or hyaluronidase and its susceptibility to HNO(2) treatment. The sulphate groups (including sulphamino and ester sulphate groups) are distributed along the polymer in the characteristic block fashion. In (3)H-labelled heparan sulphate, isolated after incubation of the cells with [(3)H]galactose, 40% of the radioactive uronic acid units are l-iduronic acid, the remainder being d-glucuronic acid. The location of heparan sulphate at the rat liver cell surface is demonstrated; part of the labelled polysaccharide can be removed from the cells by mild treatment with trypsin or heparitinase. Further, a purified plasma-membrane fraction isolated from rats previously injected with [(35)S]sulphate contains radioactively labelled heparan sulphate. A proteoglycan macromolecule composed of heparan sulphate chains attached to a protein core can be solubilized from the membrane fraction by extraction with 6m-guanidinium chloride. The proteoglycan structure is degraded by treatment with papain, Pronase or alkali. The production of heparan [(35)S]sulphate by rat liver cells incubated in the presence of [(35)S]sulphate was followed. Initially the amount of labelled polysaccharide increased with increasing incubation time. However, after 10h of incubation a steady state was reached where biosynthetic and degradative processes were in balance.

Animals↗