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Biomedical subjects

S Smeds

Publications and source records attributed to S Smeds.

At least 37 records · Page 2Linked to original sources
PubMed1991

Proliferative response of different exocrine pancreatic cells after surgical pancreaticobiliary diversion in the rat.

Pancreaticobiliary diversion (PBD) is known to induce chronic, endogenous hypercholecystokininemia causing pancreatic growth in rats. In the present study the proliferative response of the different exocrine pancreatic cells was studied by administration of 3H-thymidine, 1 mCi/kg, given 1 h before the rats were killed and 5, 10, 20, and 40 days after PBD. DNA and 3H-thymidine uptake, both expressed per 1 mg of pancreatic tissue, were significantly increased on day 5. The nuclear labeling index was increased fivefold in both the acinar and ductal cell group. In the centroacinar cell group the labeling index was increased on day 10. In conclusion, we found that the proliferative activity after PBD occurred during the first 10 days and that the ductal cells were forced into proliferation to the same extent as the acinar ones. These findings are of interest for future studies of hormonal influences on the development of pancreatic carcinoma.

Animals↗
PubMed1991

Cholecystokinin is not a major determinant for the changes in beta-cell function seen after pancreatico-biliary diversion in rats.

The influence of longterm increase in the plasma CCK levels on beta-cell function in rats was studied by using the pancreatico-biliary diversion (PBD) model. An intravenous glucose load (800 mg glucose/kg) was performed three weeks after the PBD operation. Additionally a group of PBD operated animals as well as an unoperated group received the CCK receptor antagonist L364,718 continuously during the three week study period. The proliferation rate of endocrine pancreatic cells was studied by means of 3H-thymidine administration. PBD caused a decrease in basal levels of insulin and glucose and an augmented insulin secretory response after glucose injection. There was no appreciable influence on the glucose elimination rate. When PBD animals were given the CCK receptor antagonist no differences were observed with regard to insulin and glucose compared to PBD animals without antagonist. The CCK-antagonist did not influence the beta-cell function in unoperated animals. Further, the proliferation rate of the endocrine pancreatic cells was not significantly changed in the PBD rats. The results suggest that PBD is accompanied by significant changes in basal and stimulated insulin secretion. These changes are probably not a direct consequence of the increased plasma CCK levels that follows PBD. Moreover, the insulin secretory response to glucose in normal rats was not influenced by longterm administration of the CCK receptor antagonist. Our observations should encourage further studies on the complex entero-insular interactions following pancreaticobiliary diversion.

Animals↗
PubMed1990

Proliferative response of different exocrine pancreatic cell types to hormonal stimuli. I. Effects of long-term cerulein administration.

The trophic effect on the exocrine pancreas of the cholecystokinin analogue cerulein was studied in a long-term experiment (20 or 160 micrograms/kg/24 h for 14 days) in mice by measuring changes in pancreatic weight and protein, amylase, and DNA content. Further, the selective cell growth stimulation exerted by various doses of cerulein (4, 20, 54, 160 micrograms/kg/24 h) on different exocrine pancreatic cell types was studied by continuous administration of 3H-thymidine. In the first experiment animals given 20 micrograms/kg/24 h of cerulein had increased pancreatic weight and amylase and protein content, whereas the animals given the higher dose had unchanged weight and a less pronounced increase in amylase and protein content. The pancreatic DNA content was unaffected in the 20-micrograms group but was clearly decreased by the higher dose. In the second experiment a statistically significant increase over controls was found in the fraction of labeled ductal cells when 20, 54, and 160 micrograms of cerulein was administered. However, in the acinar cell population an increase was measured only in the 160-micrograms group. A tendency to nadir in cell labeling was observed in both acinar and ductal cell groups at less stimulation. Labeling of centroacinar cells increased in all cerulein-treated groups. The results show that all cell types of the exocrine pancreas can be forced into proliferation by the cholecystokinin analogue used and that there is preferential cell growth stimulation in the ductal and centroacinar cell populations.

Amylases↗
PubMed1990

Proliferative response of different exocrine pancreatic cell types to hormonal stimuli. II. Effects of long-term secretin administration.

The effect of graded doses of secretin on exocrine pancreatic growth and cell proliferation was studied in a long-term experiment. After 16.5 and 150 micrograms/kg/24 h of secretin, each administered as two subcutaneous injections daily for 14 days, the pancreatic wet weight decreased, whereas the protein and DNA content of the gland was uninfluenced. When administered as described above for 14 days, 16.5, 50, 150, and 450 micrograms/kg/24 h of secretin did not affect the proliferation rate of ductal, acinar, or centroacinar cells as measured by a labeling index after 7 days of continuous 3H-thymidine administration. In the control groups a higher labeling index was found for ductal cells (19.9%) than for acinar cells (11.0%). During the 7 days of 3H-thymidine administration 80-90% of ductal and acinar cells remained in the G0 phase. There was a significantly higher labeling index in interlobular than in intralobular duct cells.

Amylases↗
PubMed1990

Combined cervicothoracic approach in thymectomy for myasthenia gravis.

Thymectomy was performed for myasthenia gravis on 30 patients, using a new approach with a collar incision which gave full exposure of the retrothyroid space and was directly connected to a median sternotomy. The thymus was removed en bloc without pleural incision. There was no perioperative mortality and the only complications were transient respiratory insufficiency in two cases. The postoperative hospital stay was 3-9 (mean 5.8) days. The effect of thymectomy was evaluated after 2-8 years at the Department of Neurology, when changes in symptoms (stages I-IV) or medication (need for cholinesterase inhibitors) were registered. The total clinical improvement rate was 97%, with 3% of the patients improved three stages, 33% two stages and 60% one stage compared with the preoperative classification. Twenty patients (67%) were asymptomatic at follow-up and six (20%) also required no medication. The medication need was reduced in 70% of cases (mean reduction 42%). Our cervicothoracic approach resulted in the same rate of improvement as in studies using more extensive transsternal procedures, but the morbidity was lower, with no complications requiring prolonged hospital stay. The morbidity was also less than after only transcervical procedures aiming to perform total thymectomy--a prerequisite for maximal and lasting benefit from surgery. Moreover, as this cervicothoracic approach is simple and safe, it can be recommended as an option in the surgical management of myasthenia gravis.

Adolescent↗
PubMed1989

Follow-up of two treatment modalities for ductal cancer in situ of the breast.

In a mammography screening programme for the early detection of breast cancer 66 cases of ductal cancer in situ of the breast (DCIS) were diagnosed between 1978 and 1984 and prospectively followed up. In the beginning of the study period, DCIS was treated by mastectomy without axillary clearance but sector resection has been performed increasingly. Since 1982 the latter procedure has become standard treatment. Radical resection was confirmed by specimen X-ray and histopathological examination of whole organ sections. No postoperative radiotherapy was given. Twenty-eight women had mastectomy and 38 had sector resection. The median follow-up times were 77 and 60 months respectively. In the mastectomy group postoperative monitoring did not reveal any local recurrence but one contralateral new invasive cancer was discovered. In the sector resection group five recurrences were found. Three of the latter were new cases of DCIS and two appeared as small invasive cancers (stage I). Mastectomy will cure ductal cancer in situ but has a greater morbidity. Sector resection has been established as the method of choice in stage I invasive cancer and is probably also safe in DCIS. The possible beneficial effect of postoperative local radiotherapy after sector resection for DCIS is currently being analysed in a randomized trial which started in Sweden in 1987.

Adult↗
PubMed1989

TSH binding correlates with TSH-stimulated thyroid adenylate cyclase activity in human thyroid tissues.

Thyroid-stimulating hormone (TSH) stimulates adenylate cyclase (AC) activity and the growth and differentiation of thyroid cancers of follicular cell origin. Thyroid neoplasms generally have higher TSH-stimulated AC activity than normal thyroid tissue from the same patients. To determine whether differences in TSH receptors could account for the differences in AC activity, we studied the 8000 g membrane particulate fraction from 28 thyroid tissues (10 papillary carcinomas, 6 multinodular goiters, 4 follicular adenomas, 3 follicular carcinomas, 2 Graves, 1 normal, 1 Hürthle cell adenoma, and 1 thyroiditis). TSH receptors were measured by competitive inhibition using radioactive iodine-labeled bovine TSH (125I-bTSH). Maximal binding capacity (Bmax) and dissociation constant (Kd) were calculated by Scatchard analysis. AC activity was measured by the conversion of alpha-[32P]-ATP to [32P]-cAMP in the maximally (300 mU/ml) TSH-stimulated state. The basal and forskolin-stimulated (100 mmol/L) AC activity were also measured, and the ratios to TSH-stimulated AC activity were calculated (TSH/Basal ratio and TSH/Forskolin ratio). We found a strong correlation between the percent specific binding (%SB) of 125I-bTSH and TSH/Basal ratio (r = 0.70, p = 0.0001), between Bmax and the TSH/Basal ratio (r = 0.71, p = 0.001), between %SB and TSH/Forskolin ratio (r = 0.44, p = 0.02), and between Bmax and TSH/Forskolin ratio (r = 0.65, p = 0.0002). This strong correlation between TSH binding and the TSH-stimulated AC activity suggests that in some thyroid neoplasms the higher AC response to TSH may be due to an increased number of TSH receptors.

Adenylyl Cyclases↗
PubMed1988

Plasma membrane shedding and colloid vacuoles in hyperactive human thyroid tissue.

The ultrastructural appearance of colloid vacuoles, considered to be a typical sign of hyperactivity in the human thyroid gland, was studied in human thyroid tissue transplanted to nude mice and in human thyroid tissue fixed directly after surgical removal in patients with thyrotoxicosis. Transplanted normal thyroid tissue and toxic diffuse goiter (TDG) tissue was fixed by vascular perfusion with glutaraldehyde 5 or 12 weeks after transplantation. Light microscopic quantification showed that daily injections for 2 weeks of a gamma globulin fraction of patient sera containing thyroid-stimulating immunoglobulins (TSI) greatly increased the number of colloid vacuoles in both types of transplants. The vacuoles were mainly located in the periphery of the follicle lumen, giving the colloid a scalloped appearance. Electron microscopy of TSI-exposed tissue revealed, in addition to colloid vacuoles, the presence of large amounts of membrane material in the follicle lumen. Only sparse amounts of intraluminal membrane material were present in controls. The colloid vacuoles were almost invariably associated with such membrane material, which lined the border between the vacuole and the surrounding colloid. The intraluminal material consisted of spherical and elongated formations, each structure limited by a triple-layered membrane and often containing a dense interior. The elongated structures were often of the same dimensions as microvilli. The apical surface of follicle cells in TSI-exposed tissue expressed numerous microvilli, of which many showed a similar dense interior as the intraluminal membrane structures. The intraluminal membranes frequently showed, like the apical plasma membrane of the follicle cells, a positive reaction for peroxidase. Organelles, such as mitochondria, lysosomes or rough endoplasmic reticulum, were not encountered among the intraluminal membrane structures. These observations indicate that the intraluminal membrane material is derived from the apical plasma membrane of the follicle cells, presumably by shedding of microvilli. A similar association between colloid vacuoles and membrane material was also found in thyroid tissue from patients with thyrotoxicosis fixed directly at operation. It is suggested that the presence of membrane material in the follicle lumen precipitates the formation of colloid vacuoles in hyperactive thyroid tissue. The possible involvement of intraluminal membrane material in the development of microsomal autoantibodies in Graves' disease, i.e. exposure and presentation of thyroid microsomal antigen (identical to thyroperoxidase) to the immune system, is discussed.

Animals↗
PubMed1988

The role of aspiration cytology in the management of thyroid nodules.

In the hands of an experienced cytologist aspiration cytology is a safe and hitherto the best diagnostic tool in the evaluation of nodular thyroid lesions. In histologically verified case series 50-90% of confirmed thyroid cancers can be detected by aspiration biopsy, the sensitivity being dependent on sampling errors, microscopic misinterpretation and the variation in attitude towards indeterminate diagnosis in the decision for diagnostic surgery. The number of proven benign cases that are correctly identified as such by biopsy varies accordingly and approx. 75% (specificity). In comparison with imaging procedures, including those giving information of functional activity, the combined sensitivity and specificity rates of aspiration cytology come closest to the ideal discriminatory situation. In combination with case history and careful clinical examination, fine needle aspiration cytology is the best guidance for an optimal selection of patients for therapeutic or diagnostic surgery. Future development of sensitive markers for malignant degeneration will probably increase the selective power of this diagnostic technique.

Biopsy, Needle↗
PubMed1987

Naturally occurring clones of cells with high intrinsic proliferation potential within the follicular epithelium of mouse thyroids.

The proliferation pattern of some scattered clones of naturally occurring follicular cells with an exceedingly high intrinsic growth potential was investigated in the mouse thyroid gland. In particular, evidence was sought to demonstrate that the high propensity to replicate is a stable trait transmitted from the progenitor cells to their offspring. We hypothesize that these cell clones are at the origin of the multiple adenomas that invariably arise in chronically stimulated thyroid. Growth stimulation was induced either by hemithyroidectomy or by methimazole feeding. In a first series of experiments, involving hemithyroidectomized animals, [3H]thymidine was administered continuously for 3 weeks by means of osmotic minipumps, so that all cells entering the mitotic cycle during that time were labeled. Hemithyroidectomy led to a 3-fold increase of the fraction of labeled cells in the remaining lobe. The increase was prevented by thyroxine treatment in thyroid-stimulating hormone-suppressing doses. Autoradiographs of contiguous serial sections across whole follicles showed that roughly 75% of the labeled cells were clustered in groups of 3 or more, rather than being randomly distributed. In a second set of experiments, glands stimulated by methimazole-induced thyroid-stimulating hormone hypersecretion were pulse-labeled by a single i.p. injection of [3H]thymidine. Animals were sacrificed either 2 h or 3 weeks after the administration of the label. The thyroids were excised and the fate of labeled thyroid cells was analyzed autoradiographically. In the 2-h exposure, about 95% of all labeled follicular cells were single and the remaining 5% were in pairs. In contrast, about 50% of all labeled cells were clustered in groups of 3 to 12 cells 3 weeks after the pulse labeling. The number of silver grains per nucleus was compared to that of the identically exposed controls. The intensity of label per cell appeared to be decreased in proportion to the size of the labeled clusters, indicating that clusters had generated several subsequent generations of cells. The results support previously produced evidence that highly growth-prone cells naturally occur within the normal thyroid and demonstrate, in addition, that their high intrinsic growth rate is a stable, inheritable trait. Cells which replicate at a rate faster than that of the average epithelial cell have a tendency to overgrow during goitrogenesis. They may be at the very origin of the nodules and adenomas commonly found in experimentally produced and naturally occurring goiters.

Animals↗
PubMed1987

Effects of thyroid stimulating immunoglobulin on function and morphology of xenotransplanted toxic diffuse, toxic nodular and normal thyroid tissue.

In order to examine the properties of human thyroid tissue, toxic diffuse goiter (TDG), toxic nodular goiter (TNG) and normal thyroid tissue were transplanted to nude mice. Starting 3 and 10 weeks after the transplantation the mice were given 14 daily injections of control serum or serum containing thyroid stimulating immunoglobulin (TSI). The uptake and release of 125I were repeatedly measured externally. The uptake and unstimulated release of 125I was lowest in TDG transplants, highest in TNG transplants, and intermediate in transplants of normal thyroid tissue. The findings were similar at both 3 and 10 weeks. Injections of TSI reduced the biological half-time of the tracer in TDG and normal transplants, but had no significant effect on TNG transplants. Light and electron microscopic studies showed that hyperplastic TDG tissue underwent involution after transplantation, whereas TNG and normal thyroid tissue remained unchanged. Injection of TSI reactivated TDG tissue; morphometry showed that the absolute and relative volumes of the follicle cells were more than doubled, with a corresponding decrease in the volume of the follicle lumen, and mitotic figures were common. Similar findings were seen in normal transplants, whereas the effect of TSI on TNG tissue was less pronounced. In summary, our observations show that serum from a patient with Graves' disease stimulated iodine release and induced follicle cell hyperplasia and probably also follicle cell multiplication in transplanted normal and TDG tissue, but had a lesser effect on TNG tissue.

Animals↗
PubMed1987

Vascularization of normal human thyroid tissue transplanted to nude mice.

The vascularization of normal human thyroid tissue transplanted to nude, athymic mice was examined by light, electron microscopy and autoradiography after continuous infusion of 3H-thymidine during 2, 4 and 6 days after transplantation. Labelled vascular sprouts were found in the surrounding host connective tissue after 2 days, in between peripheral follicles after 4 days and in central parts of the transplants after 6 days. The autoradiographic observations indicate that the sprouts originated from the surrounding host tissue. The amount of sprouts increased up to a maximum after 2 weeks of transplantation. At this time large interfollicular areas were occupied by sprouts. At later observations (3-5 weeks) sprouts occurred together with typical fenestrated capillaries. After 7 weeks all sprouts had differentiated into mature vessels. Our observations suggest that the transplanted thyroid tissue induces the formation of vascular sprouts in the surrounding host connective tissue. The sprouts then penetrate and vascularize the thyroid tissue.

Animals↗
PubMed1987

Graves' IgG stimulates thyroid epithelial cell proliferation in xenotransplanted human toxic diffuse goitre.

Human toxic diffuse goitre tissue was xenotransplanted to athymic mice. Transplant function was analyzed as 18 h [125I]thyroid transplant uptake at day 21 and at 10 weeks after transplantation. Graves' IgG or normal IgG was given ip daily day 22-35. Epithelial cell proliferation in the thyroid transplants was analyzed by continuous [3H]thymidine administration for 12 days between day 28 and 39 in a separate series given Graves' or normal IgG daily during the same period. The 18 h transplant uptake increased 12.8 times from 3 to 10 weeks in the Graves' IgG group but only 3.6 times in the controls (P less than 0.05). The fraction of labelled cells after [3H]thymidine incorporation was 51% +/- (SEM) after parallel Graves' IgG administration but only 2 +/- 0.3% (P less than 0.002) in the controls. The increased 10 weeks iodide uptake after Graves' IgG may be explained by an increased vascularisation or capillary maturation, by an increased individual cell sensitivity to stimulation or by an increased number of cells. Our results indicate that serum from patients with toxic diffuse goitre, i.e. Graves' IgG, contains a factor which promotes thyroid epithelial cell proliferation. Whether this is identical to TSI or is another IgG fraction remains to be shown.

Animals↗
PubMed1987

The superior laryngeal nerve in thyroid surgery.

Injury to the external branch of the superior laryngeal nerve (ESLN) during thyroid surgery can have serious consequences. A strategy for perioperative identification and preservation of the ESLN was clinically evaluated after postmortem anatomic observations. These showed that 20% of ESLNs run distally through the pharyngeal constrictor muscle, which necessitates intramuscular dissection for identification in the area around the superior thyroid pole. In 23% of the ESLNs identifiable without intramuscular dissection (18% of the total), a course partly lateral to the superior thyroid artery and its branches implied definite risk of injury during division of the superior pole vessels. In the clinical series, 72% of the ESLNs were identifiable without intramuscular dissection, and 19% of these (14% of the total) were partly lateral to the superior thyroid artery. Only one patient had signs of ESLN injury postoperatively, probably caused by diathermy to an adjacent vessel. Perioperative identification of ESLN with dissection into the pharyngeal constrictor muscle (about 20% of cases) appears to be inadvisable, but identification of ESLN with other courses is important, as around 20% are highly vulnerable during division of the superior thyroid artery and its branches.

Adult↗