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M de Jong

Publications and source records attributed to M de Jong.

At least 55 records · Page 3Linked to original sources
PubMed1997

Yttrium-90 and indium-111 labelling, receptor binding and biodistribution of [DOTA0,d-Phe1,Tyr3]octreotide, a promising somatostatin analogue for radionuclide therapy.

In vitro octreotide receptor binding of [111In-DOTA0,d-Phe1, Tyr3]octreotide (111In-DOTATOC) and the in vivo metabolism of 90Y- or 111In-labelled DOTATOC were investigated in rats in comparison with [111In-DTPA0]octreotide [111In-DTPAOC). 111In-DOTATOC was found to have an affinity similar to octreotide itself for the octreotide receptor in rat cerebral cortex microsomes. Twenty-four hours after injection of 90Y- or 111In-labelled DOTATOC, uptake of radioactivity in the octreotide receptor-expressing tissues pancreas, pituitary, adrenals and tumour was a factor of 2-6 that after injection of 111In-DTPAOC. Uptake of labelled DOTATOC in pituitary, pancreas, adrenals and tumour was almost completely blocked by pretreatment with 0.5 mg unlabelled octreotide, indicating specific binding to the octreotide receptors. These findings strongly indicate that 90Y-DOTATOC is a promising radiopharmaceutical for radiotherapy and that 111In-DOTATOC is of potential value for diagnosis of patients with octreotide receptor-positive lesions, such as most neuroendocrine tumours.

Animals↗
PubMed1997

Computer simulation to support policy making in the control of pseudorabies.

A further integration of international markets makes a coordinated policy against contagious animal infections increasingly important. In the future, stricter demands are to be expected concerning the control and eradication of such infections. To anticipate these demands, a computer simulation model is created in which scenarios can be evaluated with respect to epidemiological and economic effects of the infections and control strategies. In this paper, the simulation model is described for Pseudorabies in swine. In the model, the population of herds is subdivided into two main herd types: breeding and finishing. Each herd is in one of 24 states per herd type. The states are based on (1) the reproduction ratio R which is the number of secondary cases caused by one infectious herd, (2) the prevalence for each value of R and (3) the expected number of infectious animals in an infectious herd within each prevalence range and for each R. The different values of R are based on experiments and field data in which different vaccination strategies were used. The transition matrix with the probabilities of every transition from one state to another is calculated on a weekly base. With this matrix the distribution of herds over states from week to week is derived. To include a dynamic element in the transition probabilities, the number of newly infectious herds per week is a function of animal and other contacts, including aerial, material and personal contacts. Calculations show that the infection in the Dutch swine population will not disappear without vaccination. With a vaccination scheme in which sows are vaccinated 3 times per year and fattening pigs 1 time per cycle the infection will ultimately be eradicated, but 2 vaccinations per cycle for fattening pigs are needed to eradicate the infection within an acceptable timespan (i.e. 2 to 3 years). The latter strategy will become compulsory in the Netherlands from October 1st 1995.

Animals↗
PubMed1997

Effects of ligand priming and multiple-dose injection on tissue uptake of 111In-pentetreotide in rats.

In patients undergoing somatostatin receptor scintigraphy, treatment with octreotide (Sandostatin) is usually discontinued 24-48 h before and after injection with the radioligand 111In-pentetreotide ([111In-DTPA(O)]octreotide) (Octreoscan) because octreotide competes with radioligand for the same receptors. However, Dörr et al. and Soresi et al. reported improved visualization of carcinoid and small cell lung cancer lesions, respectively, during continued octreotide treatment. We found that intravenous administration of unlabeled octreotide to rats inhibited the binding of an optimal dose (0.5 microg) of 111In-pentetreotide to somatostatin receptors in pancreas and adrenals in a mass- and time-dependent way. Pretreatment with unlabeled octreotide never increased receptor binding of 111In-pentetreotide. Administration of 100 microg of octreotide decreased receptor-bound radioactivity if given simultaneously with or 10 or 20 min after injection of the radioligand, but had no effect if given 30 min after the radioligand. These findings indicate rapid processing of receptor-bound octreotide and suggest that octreotide treatment of patients undergoing 111In-pentetreotide scintigraphy may be reinitiated as soon as 1 h after radioligand administration.

Animals↗
PubMed1997

D-lysine reduction of indium-111 octreotide and yttrium-90 octreotide renal uptake.

UNLABELLED: Indium-111-DTPA-octreotide (111In-DTPAOC) is used successfully for imaging somatostatin receptor-positive lesions. A new and promising application is its use in peptide-receptor radionuclide therapy (PRRT). For the latter purpose, [DOTA0,D-Phe1,Tyr3]octreotide (DOTATOC), which is suitable for stable radiolabeling with 90Y, is probably even more promising. Significant renal uptake of these octreotide analogs exists, however, reducing the scintigraphic sensitivity for detection of small tumors in the perirenal region and limiting the possibilities for PRRT. We showed that the renal uptake of 111In-DTPAOC could be reduced to about 50% of control by L-lysine administration in vivo in rats. This study compares the effects of several doses and different methods of administration of D- and L-lysine, in addition to time-related effects of D-lysine, on kidney uptake of 111In-DTPAOC and 90Y-DOTATOC. METHODS: Male Wistar rats (200-250 g) were given 111In-DTPAOC (0.2 MBq, 0.5 microg-0.5 mg intravenously, intraperitoneally or orally) in the presence or absence of D- or L-lysine. At 1, 4 or 24 hr, the rats were killed, and the organs were isolated and counted for radioactivity. In different experiments, male Wistar rats (200-250 g) were given 90Y-DOTATOC (1 MBq, 0.5 microg intravenously) in the presence or absence of D-lysine. At 24 hr, the rats were killed, and the organs were isolated and counted for radioactivity. RESULTS: Administration of D- or L-lysine in a single intravenous dose of 400 mg/kg, resulted in more than 50% inhibition of kidney uptake of 111In-DTPAOC at all time points tested, independently of the mass of 111In-DTPAOC used. Higher or repeated doses of lysine did not give a significantly higher percentage inhibition. D-lysine, given orally in a dose of 400 mg/kg at 30 or 15 min before 111In-DTPAOC injection, resulted in 30% and 20% inhibition of kidney uptake, respectively. L-lysine, given orally 30 min before 111In-DTPAOC administration, resulted in 30% inhibition as well. Inhibition of kidney uptake of 111In-DTPAOC by L-lysine after intraperitoneal administration was 40%. After L-lysine administration, 111In-DTPAOC was decreased in the kidneys and in somatostatin receptor-positive organs such as the pancreas and adrenal glands. In contrast, D-lysine did not have a significant effect on uptake in octreotide receptor-positive organs. Renal uptake of 90Y-DOTATOC was reduced by 65% by intravenous D-lysine, whereas radioactivity in blood, pancreas and adrenal glands was not affected. CONCLUSION: D-lysine may be preferred to L-lysine for reduction of renal uptake of radioactivity during scintigraphy and PRRT because of its lower toxicity and because it should not interfere with the natural amino acid metabolic balance.

Animals↗
PubMed1996

Iodine-131 labelled octreotide: not an option for somatostatin receptor therapy.

Gamma-emitting radiopeptides are useful for scintigraphy of tumours on the basis of receptor binding. Likewise, beta-emitting radiopeptides may be used in radionuclide therapy of such tumours. As iodine-131 suggested to be suitable for this purpose, experiments were performed using three somatostatin analogues, in which the effects of coupling of a therapeutic dose of 131I to such peptides were investigated. This study deals with the radioiodination of very small amounts of peptide on a therapeutic scale, the required purification procedures after radioiodination, and the influence of high beta fluxes from 131I on a peptide during radioiodination and purification. Based on the regularly used therapeutic doses of 131I in cancer treatment and our previous experience with [111In-DTPA-D-Phe1]-octreotide, it was assumed that a minimal effective therapeutic dose of 3.7 GBq 131I has to be coupled to a maximum of approximately 100 microg peptide, representing only a slight excess of peptide over 131I. This contrasts with non-peptide radiopharmaceuticals in which high compound to radionuclide ratios are usually used. Labelling at low peptide to radionuclide ratios (low labelling yields) results in the formation of di-iodinated compounds, whereas at high peptide to radionuclide ratios (high labelling yields) mono-iodinated products of low specific activity are formed. Thus, after radioiodination the desired mono-iodinated peptide has to be separated from unreacted iodide, and from di-iodinated and unreacted peptide, as both compounds compete for the receptors. Possible radiolysis of the peptide during labelling and separation steps were investigated by irradiating 30 microgram unlabelled peptide with 370 MBq 131I in a small volume. The peptide composition of the incubation mixtures was investigated by high-performance liquid chromatography after irradiation for 30 min to 24 h. The results showed that the peptide was degraded with a half-life of less than 1 h. During the preparation of a real therapeutic dose (at much higher beta-flux) the peptide will be degraded even faster during the various steps required. In conclusion, intact mono-iodinated 131I-labelled somatostatin analogues for peptide receptor therapy will be difficult to obtain.

Antineoplastic Agents↗
PubMed1996

Comparison of uptake of 99mTc-MIBI, 99mTc-tetrofosmin and 99mTc-Q12 into human breast cancer cell lines.

Technetium-99m hexakis-2-methoxyisobutylisonitrile (MIBI), 99mTc-tetrofosmin and 99mTc-Q12 were all introduced for myocardial imaging but found additional applications as they are taken up by different tumours, enabling imaging of these lesions in patients. The aim of this study was to compare the uptake characteristics of these compounds in vitro in the human adenocarcinoma breast cell lines MCF-7 and ZR-75. It was shown that 99mTc-MIBI had the highest cellular uptake (15.9%+/-0.5% dose/mg protein after 60 min in MCF-7, and 14.2%+/-0.4% dose/mg protein in ZR-75), followed by 99mTc-tetrofosmin (6.8%+/-0.6% dose/mg protein in MCF-7, and 8. 2%+/-0.2% dose/mg protein in ZR-75) and 99mTc-Q12 (3.2%+/-0.1% dose/mg protein in MCF-7, and 3.5%+/-0.3% dose/mg protein in ZR-75 cells). For all three compounds tenfold differences in specific activity did not influence total cell-associated radioactivity. Uptake of 99mTc-MIBI and 99mTc-tetrofosmin was obviously lower at 4 degrees C than at 37 degrees C, whereas 99mTc-Q12 uptake showed only slight temperature dependence. When uptake was compared in cells grown to different cell densities (1 mg/ml cellular protein versus 0.3 mg/ml), no differences in uptake were detected when uptake was corrected for the amount of cellular protein present in the dishes. Furthermore, for all compounds it was shown that cellular radioactivity decreased rapidly after washing. Apart from the differences in cellular uptake of the three compounds after 60 min, no differences in residual cellular radioactivity after washing were found between the different compounds when expressed as a percentage of their 60-min uptake, suggesting that the efflux process of the radiolabelled compounds was similar. The differences in cell-associated activity after 60 min were thus presumably caused by differences in uptake. It was concluded that of the Tc-labelled compounds tested, 99mTc-MIBI had the highest cellular retention in both human breast tumour cell lines. However, for imaging in vivo not only radioactivity in the target organ is important, but also the ratio of radioactivity in the target versus that in the background. Therefore, further studies in vivo need to be performed to investigate which compound is the optimal imaging agent.

Adenocarcinoma↗
PubMed1996

Different regulation of thyroid hormone transport in liver and pituitary: its possible role in the maintenance of low T3 production during nonthyroidal illness and fasting in man.

Nonthyroidal illness (NTI) and fasting in man are characterized by a low serum concentration of T3 and an increased serum concentration of rT3. Since the serum level of T3 is one of the most important factors that determine the metabolic rate, the low serum T3 during NTI or fasting results in reduction of the energy consumption of the body. This can be regarded as an adaptive mechanism to save energy, and thus to conserve protein and to protect organ function. The low serum T3 concentration should preferentially be maintained until recovery from illness or adequate calorie supply. This implies that the low serum T3 should not result in a rise in serum TSH. We postulate that different regulation of thyroid hormone transport into the relevant tissues, i.e., liver and pituitary, may play a role in maintenance of the low T3 production during NTI and fasting. This hypothesis is further elaborated in this paper by comparing (i) the properties of the thyroid hormone uptake mechanism in rat and human hepatocytes, perfused rat liver, and rat anterior pituitary cells, and (ii) the effects of fasting and conditions that mimic NTI on thyroid hormone transport in the same preparations. In addition, the consequences of changes in thyroid hormone transport and peripheral thyroid hormone metabolism during fasting and NTI for the serum level of rT3 and for TSH secretion are discussed. The data are compatible with the existence of different transport systems for thyroid hormone in liver and pituitary. We suggest that these different thyroid hormone carriers allow tissue-specific regulation of the intracellular availability of T3.

Animals↗
PubMed1996

Uptake and metabolism of 3,5,3'-triiodothyronine and 3,3',5'-triiodothyronine by human liver-derived cells: HepG2 cells as a model for thyroid hormone handling by human liver.

The uptake and metabolism of T3 and rT3 was studied in human liver-derived HepG2 cells. The results showed a saturable, time-dependent, and ouabain-sensitive increase in nuclear bound T3. The effects of ouabain (0.5 mmol/L) and unlabeled T3 (10 nmol/L and 10 mumol/L) were much more pronounced at the nuclear level, suggesting the presence of a nonspecific component in total cellular binding. Nuclear binding of rT3 remained below the detection limit in all experiments. Comparison of rT3 metabolism in HepG2 cells and primary cultures of rat hepatocytes showed an approximately 10-fold lower iodide production in HepG2 cells. Iodide production was decreased in the presence of ouabain and almost absent in the presence of propylthiouracil (100 mumol/L). Our data confirmed the presence of a carrier-mediated uptake system for both T3 and rT3. Metabolism data indicated functional type I deiodinase activity in HepG2 cells, the presence of glucuronidating enzymes, and the absence of thyroid hormone sulfotransferase activity. Based on these data, we propose that HepG2 cells provide an appropriate model for thyroid hormone handling by human liver. In addition, we suggest that in human liver sulfation of thyroid hormone, and therefore deiodination of T3 is of only minor importance.

Animals↗
PubMed1996

Inhibition of renal uptake of indium-111-DTPA-octreotide in vivo.

UNLABELLED: Indium-111-DTPA-octreotide has been successfully used for imaging of somatostatin receptor-positive lesions. However, significant renal uptake of 111In-DTPA-octreotide exists, reducing the scintigraphic sensitivity for detection of small tumors in the perirenal region and the possibilities for radiotherapy. The aim of the present study was to determine whether renal uptake of 111In-DTPA-octreotide could be reduced in vivo in rats. METHODS: Male Wistar rats (200-250 g) were placed in metabolic cages and injected with 111In-DTPA-octreotide (0.2 MBq and 0.5 microgram octreotide), in the presence or absence of re-uptake blockers. At time t = 20 hr after injection, rats were sacrificed and organs were isolated and counted for radioactivity. RESULTS: Adding NH4Cl or NaHCO3 to the food, resulting in the production of more acid or alkaline urine respectively, resulted in less radioactivity in the kidneys 20 hr after injection compared to controls. Lysine in a single dose of 400 mg/kg resulted in an inhibition of kidney uptake of 40%. When lysine was injected 30 min before 111In-DTPA-octreotide, the inhibition was 25%. Arginine had less effect on tubular uptake of 111In-DTPA-octreotide than lysine (20% inhibition). Sodium maleate inhibited kidney uptake of 111In-DTPA-octreotide most successfully. Acetazolamide (100 mg/kg), succinylacetone (100 mg/kg), cystine dimethylester (340 mg/kg) and increase in urinary flow did not influence 111In-DTPA-octreotide retention in the kidneys. CONCLUSION: It appeared possible to reduce re-uptake of 111In-DTPA-octreotide in the rat kidney in vivo. The most pronounced effects were seen after administration of sodium maleate or lysine but, because of the described toxic effects of maleate, we will study further only the effects of lysine in a clinical setting.

Acetazolamide↗
PubMed1995

Evaluation in vitro and in rats of 161Tb-DTPA-octreotide, a somatostatin analogue with potential for intraoperative scanning and radiotherapy.

The characteristics of terbium-161 diethylene triamine penta-acetic acid (DTPA) labelled octreotide with respect to specific binding to somatostatin (octreotide) receptors on rat brain cortex membranes, biological activity, uptake and excretion by isolated perfused rat livers and metabolism in vivo in normal and tumour-bearing rats were determined and compared to those of indium-111 DTPA-octreotide. The results of the binding studies demonstrate that 161Tb-DTPA-octreotide is a high-affinity radioligand for somatostatin receptors, with an affinity comparable to that of 111In-DTPA-octreotide. Rat growth hormone secretion inhibition experiments showed that 161Tb-DTPA-octreotide has a similar potency to 111In-DTPA-octreotide. 161Tb-DTPA-octreotide appeared to be taken up even less by the isolated perfused rat liver than 111In-DTPA-octreotide, as almost no tracer disappeared from the perfusion medium. Furthermore, hardly any radioactivity was found in the liver, and excretion into the bile was negligible. The biodistribution studies showed that for octreotide receptor-positive organs, such as pancreas and adrenals, uptake of 161Tb-DTPA-octreotide is lower then that of 111In-DTPA-octreotide. However, as the clearance from the blood of the former compound is faster than that of the latter, the tissue/blood ratio is higher in the case of 161Tb-DTPA-octreotide than with 111In-DTPA-octreotide. Furthermore, these studies demonstrated that the uptake of 161Tb-DTPA-octreotide by the renal tubular cells after glomerular filtration can be reduced by administration of lysine or sodium maleate. Increase in urine production before and during the experiment had no effect on the kidney uptake of 161Tb-DTPA-octreotide.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Uptake of 3,3',5,5'-tetraiodothyroacetic acid and 3,3',5'-triiodothyronine in cultured rat anterior pituitary cells and their effects on thyrotropin secretion.

We compared the uptake, metabolism, and biological effects of tetraiodothyroacetic acid (Tetrac) and rT3 in anterior pituitary cells with those of T4 and T3. Cells were isolated from adult male Wistar rats and cultured for 3 days in medium with 10% fetal calf serum. Uptake was measured at 37 C in medium with 0.1% BSA for [125I]Tetrac (200,000 cpm; 240 pM) and [125I]T4 (100,000 cpm; 175 pM) or with 0.5% BSA for [125I]rT3 (100,000 cpm; 250 pM) and [125I]T3 (50,000 cpm; 50 pM). The free fraction of Tetrac was 1% that of T4 (in medium with 0.1 and with 0.5% BSA), and the free fraction of rT3 was half that of T3. Uptake of the four tracers increased sharply up to 1 h of incubation and then leveled off. Expressed as femtomoles per pM free hormone, uptake at equilibrium was 1.16 +/- 0.16 (n = 6) for Tetrac, 0.15 +/- 0.01 (n = 6) for T4, 0.023 +/- 0.003 (n = 6) for rT3, and 0.21 +/- 0.02 (n = 6) for T3. Cell-associated radioactivity after incubation for 24 h with [125I]Tetrac was represented for 15% by [125I]Triac; after incubation with [125I]T4 for 15-20% by [125I]T3, after incubation with [125I]rT3 for 6% by [125I]3,3'-T2, while [125I]T3 was still for 98% [125I]T3. Exposure of cells for 2 h to 100 nM TRH stimulated TSH release by 90-135%. Tetrac was effective in reducing this response at a free concentration of 0.05 pM, but rT3 was effective only at a free concentration of 16 nM. A free Tetrac concentration of 5 pM was equally effective as 50 pM free T4 in reducing the TSH response to TRH. In human serum, Tetrac was exclusively bound to T4-binding prealbumin. The free Tetrac fraction was 0.001% in control subjects and rose 2- to 12-fold in patients with nonthyroidal illness. As uptake of [125I]Tetrac in the pituitary was higher than that of T4 and T3, and it was more potent than T4 in reducing TSH release, Tetrac may be of potential significance for the regulation of TSH secretion in vivo.

Animals↗
PubMed1995

Screening of colon tumor cells and tissues for folylpolyglutamate synthetase activity.

Polyglutamylation of (anti)folates catalyzed by folylpolyglutamate synthetase (FPGS) determines the retention of these compounds in the cell. This feature is essential for the activity of folates (e.g., folinic acid) and antifolates (e.g., methotrexate) in the treatment of cancer. A FPGS assay was developed using murine liver and was based on published methods, but had a novel analytic procedure. Tritiated glutamate and aminopterin served as substrates for FPGS, and after the reaction the mixture of substrates and products was separated by thin-layer chromatography. Results were verified by standard anion-exchange high performance liquid chromatography for folates. The assay was applied to measure the activity of FPGS in several cancer cell lines and human and murine (tumor) tissues. Cancer cell lines had a much higher activity (varying from 82 to 656 pmol diglutamate formed per hour per 10(6) cells) than murine bone marrow cells (35 pmol/h/10(6) cells). Murine gut mucosa had a very low FPGS activity compared to murine liver (7 vs. 24 pmol diglutamate/h/g wet weight), but the activity in murine colon tumors was comparable to or higher than that in liver (28-52 pmol diglutamate/h/g wet weight). A screening of 11 human colon tumors or metastases demonstrated that there was a large variation in FPGS activity in this tumor type, but overall the activity was higher in tumor tissue than in normal colon mucosa. The latter feature may increase the selectivity of antifolate-based chemotherapy of colon tumors. The FPGS assay described in this paper allows large-scale screening of cell lines and tissues, because of its rapid separation procedure by thin-layer chromatography.

Animals↗
PubMed1994

Home measures of anxiety, avoidant coping and defence as predictors of anxiety, heart rate and skin conductance level just before invasive cardiovascular procedures.

The question was whether anxiety, heart rate and skin conductance level just before invasive cardiac procedures could be predicted by anxiety related measures obtained at patients homes approximately 3 weeks before treatment. Trait measures of avoidant coping and defence were provided by sixty-three male and thirty-three female patients who were scheduled for a diagnostic or interventional heart catheterization. In hospital physiological measures were registered continuously during a 20 min interview and subsequently patients reported their anxiety. Results with hierarchical regression analysis showed that sex, age, medical variables and state anxiety at home explained 62% of state anxiety in hospital. Female sex predicted high anxiety in hospital while advanced age predicted low anxiety. Medical variables and measures of coping and defence did not add a significant contribution to this prediction of anxiety. Skin conductance and heart rate measures could not be predicted by the psychological measures collected at home.

Adaptation, Psychological↗
PubMed1994

Adaptive changes in transmembrane transport and metabolism of triiodothyronine in perfused livers of fed and fasted hypothyroid and hyperthyroid rats.

The transport and subsequent metabolism of triiodothyronine (T3) were studied in isolated perfused livers of euthyroid, hypothyroid, and hyperthyroid rats, both fed and 48-hour-fasted. T3 kinetics (transport and metabolism) during perfusion were evaluated by a two-pool model, whereas the metabolism of T3 was also investigated by determination of T3 breakdown products by chromatography of medium and bile. For comparison of groups, metabolism was corrected for differences in transport. Transport parameters in fed hypothyroid livers were not significantly changed as compared with euthyroid livers, whereas metabolism was decreased. In fed hyperthyroid livers, fractional transfer rate constants for influx (k21) and efflux (k12) were decreased and metabolism, corrected for differences in intracellular mass transfer, was increased. Furthermore, for transport in hyperthyroid liver it was shown that only total mass transfer (TMT) into the metabolizing liver compartment (not into the nonmetabolizing liver compartment) was decreased. Transport and metabolic parameters in fasted hypothyroid livers were decreased as compared with euthyroid fed livers. In fasted hyperthyroid livers, transport and metabolism were not significantly different as compared with that in euthyroid fed livers, so transport was increased versus hyperthyroid fed livers. It appeared therefore that fasting normalized the effects of hyperthyroidism on both the transport and metabolic processes of T3 in the liver. The present study demonstrates normal transport and decreased metabolism in livers of hypothyroid fed rats and decreased transport and increased metabolism in livers of hyperthyroid fed rats. In livers of hypothyroid fasted rats transport and metabolism were decreased, whereas in livers of hyperthyroid fasted rats transport and metabolism were not significantly different from that in euthyroid fed livers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1994

Uptake of triiodothyronine sulfate and suppression of thyrotropin secretion in cultured anterior pituitary cells.

To investigate the uptake of triiodothyronine sulfate (T3S) and its effect on thyrotropin-releasing hormone (TRH)-induced thyrotropin (TSH) secretion, anterior pituitary cells were isolated from euthyroid rats and cultured for 3 days in medium containing 10% fetal calf serum. Incubation was performed at 37 degrees C in medium containing 0.5% bovine serum albumin (BSA). Exposure of the pituitary cells to TRH (0.1 mumol/L) for 2 hours stimulated TSH secretion by 176%. This effect was reduced by approximately 45% after a 2-hour preincubation with T3 (0.001 to 1 mumol/L). A significant inhibitory effect of T3S on TRH-induced TSH release was only observed at a concentration of 1 mumol/L. The uptake of [125I]T3 after 1 hour of incubation was reduced by 40% +/- 4% (P < .001) by simultaneous addition of 10 nmol/L unlabeled T3, whereas 1 mumol/L T3S was required to obtain a reduction of the [125I]T3 uptake by 34% +/- 2% (P < .001). The amount of T3 present in the unlabeled T3S preparation was 0.25% as determined by radioimmunoassay. When pituitary cells were incubated for 1 hour with [125I]T3S or [125I]T3 (both 50,000 cpm/0.25 mL), the uptake of [125I]T3S expressed as a percentage of the dose was 0.04% +/- 0.02% (mean +/- SE, n = 4), whereas that of [125I]T3 amounted to 3.0% +/- 0.4% (n = 4). In contrast, when hepatocytes were incubated for 1 hour with [125I]T3S, the uptake amounted to 5.1% +/- 0.8% (n = 9), whereas that of [125I]T3 was 22.1% +/- 1.7% (n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Proliferation and extracellular matrix synthesis of smooth muscle cells cultured from human coronary atherosclerotic and restenotic lesions.

OBJECTIVES: The purpose of this study was to examine the proliferative capacity and extracellular matrix synthesis of human coronary plaque cells in vitro. BACKGROUND: Common to both primary atherosclerosis and restenosis are vascular smooth muscle cell proliferation and production of extracellular matrix proteins. The applicability to humans of experimental animal models of these processes has been questioned. METHODS: Primary atherosclerotic and restenotic lesions were excised by percutaneous directional coronary atherectomy in 93 patients. Smooth muscle cells were cultivated by an explant technique and identified by their morphology in culture, ultrastructural features under electron microscopy and immunostaining using monoclonal antibodies to smooth muscle cell alpha-actin. Proliferation in secondary culture was assessed with growth curves and the synthesis of collagen and sulfated glycosaminoglycans by the incorporation of 3H-proline and 35S-sulfate, respectively. These studies were also performed in cells derived from human umbilical artery media. RESULTS: Success rates for primary (45%) and secondary (12%) culture of coronary cells were not influenced by clinical variables or lesion category. Primary culture success was improved by the presence of organized thrombus in the plaque and in relation to increased maximal cell density of the atherectomy specimen. Restenotic cells displayed more rapid growth than did cells of primary atherosclerotic origin, which grew in a manner similar to that of umbilical artery cells. Mean calculated population-doubling times for the three cell groups were 52 h (95% confidence interval [CI] 48 to 58 h), 71 h (95% CI 62 to 83 h) and 74 h (95% CI 65 to 84 h), respectively. Restenotic and primary atherosclerotic cells did not differ in the synthesis of collagen ([mean +/- SEM] 0.034 +/- 0.004 vs. 0.033 +/- 0.004 nmol isotope.microgram protein-1, p = NS) or sulfated glycosaminoglycans (11.47 +/- 1.07 vs. 15.37 +/- 3.10 nmol isotope.microgram protein-1, p = NS), but the coronary cells synthesized significantly more collagen and sulfated glycosaminoglycans than did umbilical artery cells (0.019 +/- 0.004 and 5.43 +/- 1.00 nmol isotope.microgram protein-1, respectively, both p < 0.05). CONCLUSIONS: These data indicate that increased smooth muscle cell proliferation contributes to coronary restenosis in humans and support the concept that the extracellular matrix synthesis of adult smooth muscle cells is important to lesion formation.

Cell Division↗