| 1. |
- Ander, Stefan
(författare)
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Preservation of parathyroid function in thyroid and parathyroid surgery
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Preservation of normal parathyroid function and calcium homeostasis after operations on the thyroid and parathyroid glands is a difficult assignment in endocrine surgery, and it is crucial to minimise the risks of permanent postoperative hypoparathyroidism. The aim of this thesis was to study the vascular supply of the parathyroid glands and the revascularisation, growth, and function of transplanted parathyroid tissue, in order to add new information about parathyroid preservation.The microcirculation and blood supply of normal, hyperplas~c and adenomatous parathyroid glands were studied with laser Doppler flowmetry in 103 patients during operations on the thyroid and parathyroid glands. In normal parathyroid glands the blood flow was higher compared with that in hyperplastic glands and adenomas. Occlusion of the main trunks of the inferior and superior thyroid arteries reduced the blood flow by 35% and 25%, respectively. The reduction was similar in normal, hyperplastic, and adenomatous parathyroid glands. In 12 patients with single parathyroid adenomas, the increased concentration of parathyroid hormone (PTH) remained mainly unchanged despite appreciable reduction in blood flow. In 16 patients the microcirculation and macroscopic appearance of normal parathyroid glands located anteriorly on the thyroid lobe were analysed before and after dissection for in situ preservation. There was a poor correlation between reduction in blood flow and macroscopic appearance of the glands. Laser Doppler flowmetry (LDF) showed that the disturbed microcirculation often recovered 30-60 minutes after dissection for preservation.Parathyroid tissue obtained from 47 patients operated on for hyperparathyroidism was implanted subcutaneously in athymic mice. The processes of revascularisation, morphology, cell proliferation, and function of normal, hyperplastic, and adenomatous parathyroid tissue were studied at 2 and 4 days and 1, 4, 7 and 12 weeks after transplantation. Vessels were detected by monoclonal antibodies specific for mouse and human endothelial cells. The transplanted tissues were examined by light and electron microscopy and by autoradiography after continuous infusion of tritiated thymidine. The relative amount of viable tissue was assessed with a computer image-analysing program. Graft function was judged by measuring human iPTH in mouse serum.Over 90% of the transplants took and the original structure of the tissue was well preserved. Confluent areas of parathyroid tissue could be seen in 80% of the transplants. The mean loss of viable tissue in all three groups was 45%.Immunohistochemical examination showed ingrowth of vessels from the host into the transplant. The sprouts matured gradually into vessels with thin endothelial linings and capillary fenestrations in adenomatous and hyperplastic transplants but not in transplants of normal tissue.In normal parathyroid tissue the proliferation of parathyroid parenchyma! cells increased only slightly in contrast to the advancing proliferative capacity in adenomatous tissue. In contrast to adenomas, parenchyma! cell proliferative capacity in hyperplastic tissue decreased at 12 week.Concentrations of iPTH were raised at one week in hyperplastic and adenomatous tissue. Twelve weeks after transplantation iPTH concentrations in relation to the amount of transplanted tissue and relative area of viable tissue were comparable in all three groups of transplanted tissue.We conclude that, LDF is a feasible method to study physiological blood flow in human parathyroid glands. Parathyroid blood supply is not as dependent on the inferior thyroid artery as was previously suggested. LDF showed that blood flow recovered in parathyroid glands dissected for in situ preservation and any decision about autografting should be delayed until the end of the operation. Parathyroid transplants re vascularise from host vessels and this is more pronounced and proceeds faster in hyperplastic and adenomatous tissue than in normal transplants. In contrast to nonnal and hyperplastic transplants, adenomatous tissue has a greater and increasing proliferative capacity. The iPTH concentration as an expression of parathyroid function correlates poorly with parenchyma! cell proliferation.
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| 2. |
- Andersson, Roland, 1950-
(författare)
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Appendicitis : Epidemiology and diagnosis
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study concerns appendicitis, its epidemiology and diagnosis, and the outcome of appendectomy. A population based cohort of 9,274 patients undergoing appendectomy in 1969 to 1990 in Jönköping County was retrospectively studied, and 502 patients admitted for suspected appendicitis to the hospitals in Jönköping and Eksjö between October 1992 and December 1993 were prospectively studied.Appendicitis was found to occur in outbreaks and space-time clusters, indicating an infectious etiology. The incidence of non-perforating appendicitis was strongly age-dependent, with a peak in adolescence, whereas the incidence of perforating appendicitis was stable at all ages. This suggests that perforating and non-perforating appendicitis are separate entities.There was a high rate of negative appendectomies, but during the study period an increasing diagnostic accuracy and decreasing incidence of negative appendectomies was observed, indicating a trend towards a more restrictive attitude to exploration in patients with suspected appendicitis. This was accompanied by a decreasing incidence of non-perforating appendicitis, whereas the incidence of perforating appendicitis was stable. An analysis of population based studies showed a strong relation between surgeons' attitude to exploration and the incidence of non-perforating ap9endicitis, whereas the incidence of perforating appendicitis was unrelated. This is consistent with a high proportion of potentially resolving appendicitis.A conservative management decreases the munber of negative explorations and saves a number of patients with resolving appendicitis from an unnecessary operation. This leads to a high proportion of perforations among the operated patients but the number of perforations is not increased. The perforation rate, therefore, should not be used as a quality measure of the management of patients with suspected appendicitis.The rate of negative explorations is higher in women. This gender difference is found at all ages and is not due to gynecological diseases alone. The explanation is the larger number of women attending for nonsurgical abdominal pain, whereas the rate of diagnostic errors among these patients is similar in men and women.Patients with a negative appendectomy are characterized by high intensity of pain and tenderness without signs of a systemic inflammatory response. Surgeons pay too much attention to pain and tenderness in their decision to operate, and underestimate the importance of temperature, laboratory variables and duration of symptoms.No single clinical or laboratory variable has sufficiently high discriminating power to be used as a true diagnostic test. The inflammatory variables are as important predictors as the clinical findings, and they are especially important in advanced appendicitis. Their diagnostic value is higher at a repeat examination after a few hours of observation.The study show for a need of an improved management of patients with suspected appendicitis, and the potential for improved clinical diagnosis. Inflammatory variables should be given more attention, and pain and tenderness should be interpreted more cautiously. An expectant management, with repeated clinical and laboratory examinations, is advisable once advanced appendicitis has been ruled out.
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| 3. |
- Brynhildsen, Jan, 1962-
(författare)
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Low back pain in women in relation to different exposures to female sex hormones
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Objective: To investigate the effects of increased exposition to female sex hormones and physical strain on the prevalence of low back pain (LBP) in women. To study the etJect of increased exposition to female sex hormones on spinal sagiual mobility.Background: Scientific data and clinical observations suggest an increased prevalence of LBP in women as compared with men, especially in athletes. Estrogen receptors arc present in the musculo-skeletal apparatus and in the central nervous system and female sex hormones have been suggested to affect the stability of the pelvic joints and the perception of pain. The impaired stability together with a hypermobile spine may cause increased isometric muscular work, and as a consequence, pain. Also the perception of pain may be altered by female sex hormones. Because LBP is more common in female athletes than in male athletes, increased exposition to both female sex hormones and physical strain may affect the occurrence of LBP in women. Such an exposition occurs during pregnancy, with a well-known increase in prevalence of LBP.Methods: 28 women with an increased exposition to physical strain (female soccer players) and a history of LBP underwent a clinical examination and were then observed prospectively during 6 months to study variations in the occurence and severity of LBP during the different phases of the menstrual cycle. 716 female elite athletes and 113 controls answered a questionnaire with regard to their use of oral contraceptives (OCs) and the occurrence of LBP. 1103 women, 55 or 56 years old, answered a questionnaire concerning the occurrence and severity ofLBP and use of hormone replacement therapy (HRT). 52 women with and 67 women without a history of disabling LBP during a pregnancy in 1983-84 answered a questionnaire concerning LBP during subsequent pregnancies. 24 young, healthy women were followed prospectively over a period of 12 months to measure spinal sagittal mobility before use of OCs and after 3 and 12 months of OC-use.Results: No differences were observed with regard to occurrence or severity of LBP between the different phases of the menstrual cycle or between OC-users and non-users. LBP was more common in the athletes as compared with the controls. The prevalence ofLBP was slightly increased among the HRT-users (OR 1.30; 95% CI 1.02-1.41) compared with non-users. 94% of the women with previous disabling LBP during pregnancy reported LBP in a subsequent pregnancy compared with 44% of the controls. Also concequenccs of LBP, as sick-leave, were more common in the group of women with disabling LBP during a previous pregnancy. No change in spinal sagittal mobility was observed in the group of women before and after the women began to use OCs.Conclusions: Use of oral contraceptives does not seem to increase the prevalence of LBP. There is nothing in our results to suggest that women with LBP with an unspecific origin should discontinue their use of oral contraceptives. Postmenopausal women who use HRT had a slightly increased prevalence of LBP, but this increase is probably of no clinical significance. Women who had suffered from LBP during a previous pregnancy run a high risk for LBP in the future, both during a subsequent pregnancy and during the non-pregnant state. Increased exposition to exogenously administered female sex hormones does not increase spinal sagittal mobility in young, healthy, nullipareous women.
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| 4. |
- Dabrosin, Charlotta
(författare)
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Effects of sex steroids on normal human breast : studies in vivo using microdialysis and in vitro in cell culture
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Prolonged exposure to sex steroids may constitute a risk factor for the development of breast cancer. The biological mechanisms involved in breast carcinogenesis are not well understood.Basic knowledge of sex steroid effects on the normal human breast is still limited, one reason being the lack of an available in vivo technique for investigations of breast tissue metabolism.In this study, the microdialysis technique was developed and evaluated as a method for measurements of tissue-specific concentrations of amino acids, lactate, pyruvate and glutathione in normal human breast tissue during the menstrual cycle. The technique was successfully applied to breast tissue and it was observed that the concentrations of several amino acids as well as glutathione changed during the menstrual cycle. Oxidative damage to cells is one of the mechanisms which may be involved in the development of breast cancer. Normal aerobic metabolism generates potentially dangerous oxidants which are controlled by a variety of antioxidant systems. The exact regulatory mechanisms of these systems are not yet fully understood. We studied the effects of estradiol and progesterone on antioxidative activity in normal human breast tissue, in vivo with the microdialysis technique, and in vitro using normal human breast epithelial cells in culture. The in vivo levels of the antioxidant glutathione were measured early and late in the menstrual cycle in breast tissue and subcutaneous fat. The glutathione levels were higher late in the menstrual cycle in both tissues, when the serum levels of estradiol and progesterone were high. In vitro, breast epithelium exposed to estradiol and progesterone exhibited decreased activity of the antioxidative enzymes catalase and glutathione reductase, whereas the activity of glutathione peroxidase tended to increase compared with cells grown in medium without added sex hormones. The vulnerability to oxidative stress, induced by hydrogen peroxide, increased in cells grown with estradiol and progesterone present in the media. α-Tocopherol, and α-tocopherol in combination with ascorbic acid, but not ascorbic acid alone, protected from cell death induced by hydrogen peroxide. This effect was not dependent on estradiol and progesterone exposure.In conclusion, the data suggest an effect of estradiol and progesterone on antioxidative activity in normal human breast tissue both in vivo and in vitro.Microdialysis will be a useful tool in future research of these and other aspects concerning human breast tissue.
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| 5. |
- Dabrosin-Söderholm, Johan, 1958-
(författare)
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Epithelial barrier dysfunction in ileal Crohn's disease
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study aimed at investigating the intestinal barrier in Crohn's disease, with special reference to epithelial responses to luminal stimuli, and to permeation of proteins.Ileal mucosa from patients undergoing intestinal resection was studied in vitro in Ussing chambers. Intestinal permeability was also studied in vivo, by oral load of lactulose and mannitol.The Ussing chamber was evaluated for intestinal barrier studies. Normal ileal mucosa from patients with colon cancer was subjected to long-term experiments, and investigated in regard to various viability parameters. Mucosal permeability, structural integrity and metabolism were maintained for 90 minutes, and specimens with poor viability were detected by a low transepithelial potential difference. In rat ileal mucosa, luminal sodium caprate, a constituent of milk fat, induced dilatation of the tight junctions as visualised by electron microscopy, and a reversible increase in tight junction permeability. The findings indicate that the Ussing chamber is suitable for studies of the intestinal barrier, including tight junction regulation, provided that experiments are monitored by measurements of transepithelial potential difference and are limited in time.In vitro studies of human ileal mucosa showed that luminal sodium caprate caused uncoupling of oxidative phosphorylation, as shown by a fall in epithelial ATP contents, and mitochondrial swelling seen by electron microscopy, paralleled by an increased permeability. Non-inflamed Crohn's disease specimens had an exaggerated permeability increase and an augmented fall in transepithelial electrical resistance. Confocal microscopy revealed rearrangements of perijunctional filamentous actin, causing dilatation of the tight junctions. In Crohn's disease, a more pronounced reorganisation of actin filaments was seen, suggesting the tight junctions to be hyperreactive to luminal stimuli due to a disturbed cytoskeletal regulation.In vivo, an increased intestinal permeability was induced by ingestion of acetylsalicylic acid. One third of both Crohn's disease patients and their first-degree relatives showed an augmented permeability increase, whereas spouses were equal to controls, suggesting a genetically determined vulnerability of the intestinal barrier.In vitro, non-inflamed ileum from Crohn's disease patients had an increased permeation of ovalbumin. Confocal microscopy suggested this to be caused by an augmented transcytosis, a previously unrecognised defect in the epithelial barrier in Crohn's disease, with a subsequent exposure of antigenic proteins to the subepithelial immunocytes.The Crohn's disease patients without residual inflammation after surgery were followed with endoscopy within twelve months, and all revealed recurrent ileal inflammation.The study indicates a perturbed intestinal barrier in Crohn's disease, possibly genetically determined. The impaired barrier function is demonstrated both by an augmented epithelial transcytosis and by hyperreactive tight junctions. The epithelial barrier dysfunction precedes the recurrent intestinal inflammation in ileal Crohn's disease. The findings suggest an interplay between an impaired epithelial barrier and luminal factors in the initiation of intestinal inflammation.
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| 6. |
- Druid, Henrik
(författare)
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Experimental acute ischemic renal failure and anticoagulation
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on experimental studies on acute renal failure (ARF) in rats. The model employed is that of renal artery clamping, which causes a standardized, ischemic trauma to the kidney. The proximate objective of the investigations was to study iflocal coagulation in the kidney may be induced by a pure ischemic trauma, and whether such a coagulation could be of importance for the development of ARF in this experimental model.The content of isotope-labeled fibrinogen and albumin was determined in postischemic kidneys and controls. After 60rnin of unilateral ischemia, the fibrin(ogen)/degradation products (FIB) and albumin content of the kidney increased rapidly and significantly, approximately averaging 200% of controls. The total kidney weight increased only to 130% of controls. Pretreatment with heparin in a dose of 2000 IU/kg BW, markedly attenuated the increase in kidney weight and content of FIB and albumin.Pretreatment with a lower dose of heparin, 400 IU!kg BW, and warfarin (given intraperitoneally 24 h before the experiment) produced a similar reduction of these parameters, whereas pretreatment with a heparin analog, devoid of anticoagulant effect, did not.In post-ischemic kidneys, scanning electron microscopy (SEM) of cautiously handled freezedried tissue revealed granular and fibrillary material in the tubules and in Bowman's space, at some locations displaying prominent network patterns. Immunofluorescence against FIB showed immunoreactive material in vasa recta, the peritubular capillaries, Bowman's space and in the tubules. By transmission electron microscopy (TEM), fibrin strands lacking periodicity were seen. As compared to controls, the postischemic kidneys generally showed a marked dilatation of Bowman's capsule. No fibrin deposition was seen in heparin pretreated animals.To determine if anticoagulation exerts the described effects by prevention of tubular obstructions or by attenuation of increased glomerular permeability, morphometry of glomeruli was performed by light microscopy and TEM Postischemic kidneys from rats pretreated with saline showed a marked widening of Bowman's space, most likely due to tubular obstruction, whereas Bowman's space width in anticoagulated rats did not differ from controls. Structural changes of the podocyte foot processes as a marker of increased macromolecular permeability were severe in both saline pretreated and anticoagulated kidneys.Glomerular filtration rate fell to 6% of controls after 40 min of ischemia. Warfarin-pretreatment attenuated this decrease significantly. Urinary protein excretion increased in both salinepretreated and anticoagulated rats. The excretion of FIB was significantly increased in warfarinpretreated rats, consistent with the previous observation of an attenuation of FIB content of postischemic kidneys by anticoagulation. This result thus suggests that warfarin did not prevent macromolecular sieving, but reduced the formation of protein-containing tubular casts.In summary, these studies show that a pure ischemic injury to the kidney results in a local coagulation in the kidney, most prominently within Bowman's space and in the tubules. It is suggested that the increased glomerular permeability to macromolecules causes sieving of fibrinogen, which may precipitate in Bowman's space and tubuli and promote the development of tubular obstructions.
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| 7. |
- Gottvall, Eva
(författare)
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The direct current electroretinogram and the standing potential of the rabbit under different stimulus and adapting conditions
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The electroretinograrn (ERG) reflects the summation of electrical responses generated by neurons and non-neuronal cells in the retina and pigment epithelium in response to light. The major ERG components are the fast, negative a-wave, the fast, positive b-wave and the slow, positive c-wave. The ERG is superimposed on the standing potential of the eye (SP).Experiments were performed on albino and pigmented rabbits under general anesthesia. The aim was to study the development of the ERG with time in response to repeated light stimuli of different intensities (Paper I) or different interstimulus intervals (Paper II). The effects of a prolonged uniocular dark adaptation period (Paper III) and the influence of possible diurnal rhythms (Paper IV) were investigated, as was the long-term development and reproducibility of the ERG in experiments performed on consecutive days (Paper V). The influence of intravitreally injected dopamine at different concentrations on the development of the ERG was also studied (Paper VI).When using light stimuli of high intensity and short interstimulus interval (Papers I and II) the c-wave amplitude was immediately reduced after the first stimulus, but recovered to a large extent. The parallel behavior of the c-wave and SP suggested the presence of a pigment epithelial mechanism behind the recovery of the c-wave. The a- and b-wave amplitudes were immediately reduced, but recovered only to a limited extent. The final amplitudes of the b-and c-waves and to a large extent also of the a-wave seemed to be fairly independent of stimulus intensity.When one eye was dark adapted and the other eye simultaneously exposed to repeated widely spaced light stimuli of moderate intensity (Paper III) the b- and c-wave amplitudes of the unoccluded eye slowly increased during the course of several hours, but the a-wave amplitude was more stable. When the cover was removed from the previously occluded eye the a- and b-wave amplitudes immediately attained the level of those recorded from the contralateral eye, which had been light adapted by the stimuli. The phenomenon may suggest a mechanism for transfer of information between the eyes.The development of the ERG amplitudes and the SP was studied during the course of the day by repeating identical series of light stimuli every hour, and by commencing the experiments at different points of time (Paper IV). The amplitude of the b-wave did not reach relative stability until 2.5 to 3.5 hours after the beginning of dark adaptation, and that of the cwave continued to rise throughout the experiments. Since the pattern was similar in experiments starting in the morning and in the afternoon, it seems less probable that diurnal rhythms caused the findings.The long-tenn development of the ERG during several hours of stimulation with light of high intensity was studied in identical experiments performed on consecutive days (Paper V). In addition to the findings described in Papers I and II, a peak in the b-wave amplitude was observed 20-21 min after the start of light stimulation. There were no significant differences between experiments performed on consecutive days.The effects of intravitreally injected dopamine of different concentrations on the development of the ERG was studied in Paper VI. During exposure to repeated light stimuli of moderate intensity the b- and c-wave amplitudes were reduced with a decreased or even abolished amplitude increment with time in the eye injected with dopamine, and the responses were related to the concentration of the drug. The peaks in the b-and c-wave amplitude seen in the control eye when frequent stimuli of high intensity were used were abolished in the eye injected with dopamine at higher concentrations of the drug. Thus, dopamine may affect the adaptive process of the retina.
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| 8. |
- Grenegård, Magnus, 1963-
(författare)
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Platelets : intracellular signalling and cellular interaction
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Activation of platelets is essential to prevent excessive blood loss at the site of vascular injury. These highly reactive cell fragments are also involved in several pathological conditions, in particular arterial thrombosis, which, in the coronary vessels, can lead to reduced blood flow, vessel occlusion and myocardial infarction.The present research was focused on the anti-platelet properties, mechanisms of actions, and interactions of GEA 3175 and adenosine. The former a novel nitric oxidecontaining and cyclic GMP-elevating compound, the latter a cyclic AMP-elevating · purine nucleoside. Separately, the two substances significantly reduced the cytosolic , Ca2+ responses, but only marginally suppressed subsequent functional responses in thrombin-stimulated human platelets. However, coadministration of the compounds synergistically inhibited platelet aggregation and abolished dense granule secretion 1 and exposure of P-selectin, and also markedly reduced binding of fibrinogen to the i surface of platelets. The results imply that the stronger inhibition of platelet functions was due to potent blocking of the initial Ca2+ transient and abrogation of mechanisms involved in the influx of extracellular Ca2+. Together, the findings clearly manifest the importance of an interaction between different inhibitory intracellular pathways in order to completely suppress the activity of tbrombin activated platelets.Cell- and drug-comparative studies revealed that GEA 3175 provoked aremarkable long-acting inhibition of contractile responses and a concomitant i sustained increase in cyclic GMP levels in airway smooth muscle tissue. The mechanisms of relaxation involved iberiotoxin-sensitive K + channels and okadaic ' acid-sensitive phosphatases. Separately, GEA 3175 and adenosine markedly inhibited the respiratory burst in chemoattractant-activated neutrophil granulocytes. Opposite to the situation in platelets, the two compounds did not interact synergistically and coadministration had only a negligible effect on cytosolic Ca2+ signals in neutrophils. These data clearly demonstrate cell type-specific responses to cyclic GMP- and cyclic AMP-elevating agents.This thesis also delineates the regulatory effects of platelets on neutrophil cellular and intracellular responses. Simple mixture of suspensions of human platelets and neutrophils caused prominent changes in the neutrophil in regard to cytoskeletal arrangement, cytosolic Ca2+ responsiveness, and capacity to generate reactive oxygen species. Platelet-derived factor(s) induced a marked suppression of the respiratory burst in activated neutrophils, an effect attributed to peripheral accumulation of ! filamentous actin and enhanced release of endogenous adenosine from the neutrophil. The chemotactic-peptide-induced rise in cytosolic Ca2+ in neutrophils was dramatically amplified in the presence of platelets, and ATP released from the platelets may play a role in this priming phenomenon, However, additional experiments showed that the amplified Ca2+ response was virtually independent of the state of activation of the platelet, required extracellular Ca2+ ions, and was completely insensitive to the NO-donor GEA 3175. Further analysis strongly indicated that platelets affected the cyclic AMP-sensitive phase of the Ca2+ response in neutrophils. In conclusion, multiple mediators and mechanisms participate in the platelet-mediated modulation of neutrophil responses, and greater understanding of the complex mechanisms and consequences of the interactions between these blood cells may provide useful information for the design of pharmacological tools and methods to control the inflammatory reaction.
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| 9. |
- Herbertsson, Helena, 1967-
(författare)
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Studies on a novel cytosolic/nuclear binding protein for the eicosanoid 12(S)-hydroxyeicosatetraenoic acid
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hydroxyeicosatetraenoic acids (HETEs) are lipoxygenase metabolites of arachidonic acid. HETEs were long considered to have few or no important biological function - a view that proved to be incorrect. These compounds have now been identified in many different types of cells, and they have been attributed several important actions, the molecular mechanisms of which are largely unclear. This thesis describes the discovery of a putative receptor for 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid (12(S)-HETE).Specific high-affinity binding sites for 12(S)-HETE were detected in the cytosol (52%) and the nuclei (18%) of cells of the Lewis lung carcinoma (LLC) line. Similar l2(S)-HETE binding sites were detected in the cytosol of several other kinds of cells and in human platelets. Gel permeation chromatography and density gradient centrifugation indicated an apparent molecular weight of about 650 kDa and a sedimentation coefficient of20.5 S for the binding sites in the cytosol ofLLC cells. Treatment with ATP caused the 650 kDa component to dissociate into subunits. The actuall2(S)-HETE binding subunit was subsequently shown to have a molecular weight of about 50 kDa.The subcellular distribution of l2(S)-HETE binding sites in LLC cells was found to resemble the distribution of some nuclear receptors of the steroid hormone receptor superfamily. The untransformed glucocorticoid receptor has been reported to be located in cytosol in association with heat shock proteins 70 and 90, and Western blot analyses and immunoprecipitation revealed the same two proteins in the cytosolic 650 kDa l2(S)-HETE binding complex.A possible relationship to the steroid hormone receptor superfamily was also suggested by the observation that the 50 kDa l2(S)-HETE binding protein interacted with steroid receptor coactivator-l (SRC-l), which is known to be recruited to the site of transcriptional activity by several nuclear receptors. The interaction with SRC-1 occurred only when l2(S)-HETE was bound to its 50 kDa binding protein.In summary, the research presented in this thesis led to the discovery of a novel type of eicosanoid receptor. This binding site resembles the nuclear receptors for steroids and related compounds by virtue of its subcellular distribution, the inclusion of heat shock proteins in its binding complex, and its strictly ligand-dependent interaction with SRC-l.
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| 10. |
- Håkansson, Annika, 1962-
(författare)
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Interferon-alpha based treatment of metastatic malignant melanoma : Effect of immune parameters of importance for monitoring immunotherapy
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cutaneous malignant melanoma is a rapidly increasing disease. Most patients are cured by surgical excision of their primary tumour, but for patients with metastatic disease the prognosis is still very poor despite various attempts with chemotherapeutic agents, and during the last decade with immunotherapy, using several different biological agents alone or in combination. Thus, there is a great need for a better understanding of various functions of the immune system, tools for monitoring immunotherapy and predictive tests for choosing patients who are suitable for this therapy.The aims of the present investigation was therefore to study factors of possible importance for the immune control of tumours such as the occurrence and distribution of tumour-infiltrating mononuclear cells, expression ofTNFa, ICAM-1 and down-regulation of the function of tumour-infiltrating mononuclear cells. Using fine-needle aspiration of melanoma metastases we show a correlation between the occurrence of CD4+ lymphocytes in the metastases and the therapeutic benefit ofiFN-a. Thus, the degree of infiltration of these cells seems to be a useful predictive test for choosing patients suited to this therapy. We report that the expression of ICAM-1 on tumour cells is up-regulated after IFN-a treatment and describe a correlation between the expression of ICAM-1 by tumour cells and infiltration of CD4+ lymphocytes in the metastases. Thus, deternllning of ICAM:- 1 expression by tumour cells obtained by fine needle aspiration could perhaps be a valuable supplement to detennining the occurrence of tumour-infiltrating CD4+ lymphocytes tocorrelate with the response to IFN-a treatment.We demonstrate a low immune reactivity in melanoma metastases with a high expression of TNF-a by the tumour cells in untreated metastases and that IFN-a treatment could increase the immune reactivity. We also demonstrate that during the second week ofiFN-a treatment tumour-infiltrating CD4+ lymphocytes migrate from the stromal areas into the tumour nodules, close to the tumour cells, and that the extent of the tumour areas with regressive changes was significantly enhanced compared to untreated patients. Markers of the function of tumour infiltrating lymphocytes, the ~-chain and CD28, were found to be down-regulated, especially in areas of extensive tumour regression. Taken together our results are compatible with the view that the immunostimulating effect of IFNa, resulting in immune-mediated tumour cell destruction, occurs early during the treatment period and is followed within a few weeks by down-regulation of the anti-tumour immune response. Thus, in immunotherapy the possibility of inducing immunosuppression due to the lysis of tumour cells and the release of immunosuppressor factors should be considered and monitored.
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