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Biomedical subjects

S Smeds

Publications and source records attributed to S Smeds.

80 records · Page 5Linked to original sources
PubMedDate not supplied

Human parathyroid blood supply determined by laser-Doppler flowmetry.

The blood supply of 53 normal human parathyroid glands was studied with laser Doppler flowmetry in 45 patients undergoing operations on the thyroid and parathyroid glands. The inferior and superior thyroid arteries and other vessels that might supply the parathyroid glands were occluded so their contribution to parathyroid perfusion could be studied. Occlusion of the main trunk of the inferior thyroid artery resulted in a reduction of blood flow by one-third, and a similar reduction was obtained after occlusion of the superior thyroid artery. The results demonstrate that the blood supply to the parathyroid glands is not as dependent on the inferior thyroid artery as has previously been suggested but that other routes of blood supply may be equally or, in some cases, even more important.

Arteries↗
PubMedDate not supplied

Surgery for hyperthyroidism: hemithyroidectomy plus contralateral resection or bilateral resection? A prospective randomized study of postoperative complications and long-term results.

Fifty consecutive patients undergoing surgical treatment for hyperthyroidism were randomized to have either bilateral subtotal resection (n = 23) or hemithyroidectomy plus contralateral resection (n = 27). No significant differences in operating time or intra-operative bleeding were found. No postoperative bleeding and no temporary or persistent recurrent laryngeal nerve paralysis occurred. Four patients who underwent bilateral resection and 2 patients who had hemithyroidectomy resection needed temporary calcium supplementation, and the serum calcium concentrations were slightly lower during the first few postoperative days in the patient undergoing hemithyroidectomy/resection. No persistent hypocalcemia occurred in either of the groups. At follow-up 3-4 years (mean 3.6 years) postoperatively, 1 patient in the bilateral resection group developed recurrent hyperthyroidism; no patients in the hemithyroidectomy/resection group developed recurrent hyperthyroidism. Twelve (44%) patients in the hemithyroidectomy/resection group and 8 (35%) patients in the bilateral resection group needed thyroxine supplementation because of a rise in thyroid stimulating hormone concentration combined with clinical signs of hypothyroidism that developed during follow-up. Hyperthyroidism can be treated by hemithyroidectomy plus contralateral resection without increasing the risk of complications. The results also suggest that when using this method, a slightly larger thyroid remnant should be left to avoid an increase in the incidence of hypothyroidism postoperatively.

Adult↗
PubMedDate not supplied

The nude mouse. A possible experimental model for investigation of human thyroid tissue.

The effect of transplanting hyperfunctioning human thyroid tissue to athymic, nude mice was explored. The thyroid tissue was obtained from a patient with diffuse, thyrotoxic goiter preoperatively treated with a beta-adrenoreceptor blocker. One transplant was placed in each groin of 4 nude mice. Light microscopy after 4 weeks showed that transplants consisted mainly of typical follicles; capillaries were common at the periphery of the transplant but not in between the follicles. The ultrastructure of the follicle cells in the transplants was similar to that of follicle cells in general. All 8 transplants accumulated 125I as revealed by external counting; the uptake in each transplant 24 h after administration of radioiodine was 4-25% of that in the thyroid of the transplanted mouse. The release of radioiodine, measured during a period of 14 days, from the thyroid of a transplanted mouse was delayed as compared to a nontransplanted control; this indicates that the mouse thyroid activity was suppressed due to hormone production in the transplants. Electron microscopic autoradiography 24 h after injection of 125I showed that protein-bound label in transplants was located mainly in follicle lumens. The radioiodine was incorporated in thyroglobulin as demonstrated by separation of soluble proteins from transplants by sucrose density gradient centrifugation. The present study shows that human thyroid tissue can be transplanted to nude mice with maintained structural and functional properties. Transplantation of human thyroid tissue might be a useful model for studies of thyroid diseases.

Animals↗
PubMedDate not supplied

Microdialysis of 5-S-cysteinyldopa from interstitial fluid in cutaneous human melanoma transplanted to athymic mice.

Microdialysis was investigated as a tool for the determination of the extracellular concentration of the pigment metabolite 5-S-cysteinyldopa in human melanoma transplanted to athymic mice. Histology of the tumour with the microdialysis probes in situ showed no tissue damage. With probes equipped with polycarbonate membranes (20 kD) extraction (relative recovery) was approximately 50% at pH 4.0 and flow rates of 1 microliter/min, but at pH 7.0 recoveries were markedly lower, particularly from serum. In a first series of human melanomas transplanted to athymic mice low concentrations of 5-S-cysteinyldopa were detected in only two out of ten dialysates and were not detected in the other eight. Utilizing devices constructed for comparison of membrane characteristics in vitro we found about 4-fold higher recoveries with cuprophane and polyamide membranes than with polycarbonate membranes. Therefore newly constructed microdialysis probes (CMA/11) with cuprophane membranes were tested in vitro and gave recoveries of 38-48% from Ringer-Acetate solutions and 22-31% from serum, and the pH effects were low. When these probes were utilized in a second series of melanomas transplanted to athymic mice, 5-S-cysteinyldopa could easily be quantified in 10/10 experiments. A steady-state level of the dialysate 5-S-cysteinyldopa concentration was reached after 45 min.

Animals↗
PubMedDate not supplied

A high-sensitivity fluorometric high-performance liquid chromatographic method for determination of glutathione and other thiols in cultured melanoma cells, microdialysis samples from melanoma tissue, and blood plasma.

A high-performance liquid chromatographic method with fluorometric detection is described which is suitable for determination of glutathione in small samples. Reduced glutathione (GSH) and total glutathione obtained as GSH after reduction with glutathione reductase is derivatized with N-(7-dimethylamino-4-methyl-3-coumarinyl) maleimide (DACM) and subjected to chromatography. The detection limit for the GSH-DACM derivative was 5-10 fmol/injection, and analytical recovery was quantitative. The method is suitable for determination of both reduced and total glutathione in samples from microdialysis of melanoma tumours, and cysteine can be quantified in the same chromatogram. Application is shown also for glutathione determinations in cultured melanoma cells, melanoma homogenates and plasma.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Relationships between thyroid hormone and catecholamines in experimental trauma.

The relationship between thyroid hormones (T4 and T3) and the catecholamines (adrenaline and noradrenaline) was studied as regards the possible value of administered T3 in the treatment of severely injured patients. Preparative surgery was performed on 36 pigs, 26 of which were then submitted to a standardized high-energy missile trauma to a hind leg. In 14 of the latter group, infusion of T3 was begun immediately before the trauma (n = 6), or after a delay of 8 h (n = 4) or 24 h (n = 4). A correlation was found between the disappearance rate of T3 and T4 and the catecholamine release, r = 0.79 (p less than 0.001) for adrenaline and 0.64 (p less than 0.01) for noradrenaline. T3 infusion started immediately before high-energy trauma resulted in raised serum levels of catecholamines, mainly noradrenaline, and was associated with a high mortality (4/6), and a clinical picture resembling thyrotoxic crisis. At 8 h the catecholamine-response to T3 administration was blunted and at 24 h post-trauma no influence on catecholamine levels could be determined. The high correlation between adrenaline release and disappearance rates of T3 and T4 after trauma suggests that adrenaline may in some way be connected to the fall in serum T3 and T4 concentrations following major trauma. The results further accord with the suggested role of T3 as a false neurotransmitter. Administration of T3 in the initial phase of the "low T3 state", presumably would not be of benefit for the severely injured patient.

Animals↗
PubMedDate not supplied

Effects of portal glucose infusion on thyroid hormone concentrations in serum after high energy trauma in pigs.

The effect of portal glucose infusion on serum thyroid hormone levels was studied in five anaesthetized pigs during 48 h observation in an intensive care unit following standardized high energy trauma. At 10-18 h post-trauma, and again at 28-36 h, 100 g glucose was infused into the portal circulation via a splenic vein. In six animals, otherwise treated in the same way, the glucose infusions were given via a peripheral venous catheter. During portal glucose infusion at 28-36 h post-trauma, serum T3 rose significantly above the level in the controls. After termination of the portal glucose infusion, the serum concentration again fell. At 48 h the rT3 concentration was significantly lower in the pigs given portal glucose than in the control pigs. It was concluded that portal, but not peripheral, glucose infusion can temporarily reverse the trauma-induced change in triiodothyronine metabolism. This indicates that increase of the splanchnic, and more specifically the hepatic, glucose concentration could be important for amelioration of the low T3 state.

Animals↗