| 21. |
- Hyllienmark, Lars
(författare)
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Influence of metabolic disturbance on nervous function : clinical and experimental studies
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present work consists of clinical and experimental studies and describes some effects of metabolic disturbance on nervous function. It is an electrophysiological examination of both single cells and patients exposed to metabolic insult or disease. The patch-clamp technique has been used for measurements of whole-cell currents in rat brain slices and studies of nerve conduction has been used as a clinical test on peripheral nervous function in young patients with insulin-dependent diabetes mellitus (IDDM).The objective of the clinical studies was to find out to what extent young IDDM patients with multiple insulin injection therapy (MIT) still develop peripheral nerve dysfunction and to elucidate the reason why.The objective of the experimental studies was to evaluate the effect of metabolic disturbance - induced chemically or by anoxia - on the membrane potential and the ionic conductances in hippocampal CA1 pyramidal cells.It is concluded that(1) despite MIT-treatment and good metabolic control nerve dysfunction is still common in an unselected group of children and adolescents with IDDM(2) the most important risk factors for nerve dysfunction in IDDM arc increased height and poor long-term metabolic control(3) metabolic inhibition at 22-24°C or anoxia at 33-34°C causes hyperpolarization and changes in the function of several types of K+ channels in CA1 pyramidal cells(4) a change in membrane potential by a few millivolts inhibited the spontaneous impulse firing(5) a transient opening of tolbutamide-sensitive K+ channels could explain the increase in grest and the hyperpolarization observed in most cells during metabolic inhibition(6) by this mechanism the excitablity decreases which may diminish the energy demand in cortical cells during different types of metabolic insult.
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| 22. |
- Jendle, Johan H.
(författare)
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Intrapulmonary insulin : Experimental and clinical studies
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- After intrapulmonary insulin administration was first reported in 1925, the development of highly efficient nebulisers has once again made this area interesting. Therefore, the distribution and retention of aerosol produced by a new jet nebuliser was evaluated in an animal model. Anaesthetized and mechanically ventilated pigs were given radiolabelled aerosol, insulin or the combination of insulin and a surface active agent. After sacrifice the lungs were histologically examined or scintigrafted using a gamma camera. The distribution of aerosol was even and reached the peripheral parts of the lung parenchyma. The retention of insulin was estimated to be 36%. No morfological changes were observed. The biological effects of intrapulmonary insulin administration were evaluated in 14 pigs in a double-blind placebo controlled randomized intervention trial. Insulin at a dose of 10 and 40 U as well as 0.9% saline solution was given as aerosol. The blood glucose and serum insulin concentrations were assessed at certain intervals during 90 min. The mean blood glucose concentration fell from 4.6 ± 0.1 to 2.8 ± 0.2 mmol/L reaching a nadir 40 min after the start of nebulisation. Serum insulin rose from 5.2 ± 0.1 to 25 ± 9 mUlL. Eight healthy volunteers received insulin aerosol in three different doses (40, 80 and 160 U) in a double-blind randomized intervention study. As a control saline solution was given. Blood glucose, serum insulin and serum C-peptide were assessed during 120 min. A reduction of the mean bloodglucose concentration was seen, falling from 4.3 ± 0.2 to 2.8 ± 0.2 mmol/L after 160 U. Serum insulin rose from 9.5 ± 1.5 mUlL to 26.1 ± 2.5 mUlL. Serum C-peptide was suppressed in a dosedependent fashion. Twelve patients with NIDDM treated with anti-diabetic drugs were given intrapulmonary insulin in a double-blind randomized intervention trial. Insulin was given at a dose of 2.5 U/kg BW. As a control saline solution was given. Blood glucose, serum insulin and serum C-peptide were assessed during 180 min. Blood glucose fell from 10.2 ± 0.5 to 6.1 ± 0.5 mmol/L. Serum insulin rose from 11.2 ± 1.8 to 28.0 ± 2.6 mUlL. Likewise serum C-peptide was suppressed after inhaling the insulin aerosol. A flow cytometric assay was developed to assess the changes of the F-actin content and DNA synthesis in adherent cells after short-time and long-term stimulation with insulin and PDGF. No stimulatory effect on the DNA synthesis was seen on lung fibroblasts after repetitive insulin treatment. Thus, intrapulmonary insulin administration has been evaluated in experimental and clinical studies. Significant lowering of the blood glucose concentrations and clinically relevant serum insulin concentrations were achieved. No subjective adverse effects were reported. No changes in lung function could be observed experimentally.
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| 23. |
- Johansson, Carina S.
(författare)
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Development and aging of nerve fibres in the rat inferior alveolar nerve
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Structural and functional properties of nerve fibres in the rat inferior alveolar nerve (IAN) were examined during development and aging.Rat molar pulpal expllints influence neurite outgrowth from perinatal rat trigeminal ganglion explants, eo-cultured in vitro. Three patterns were found: The A-pattern, where neurites grew in all directions, predominated. In some cultures, the highest density of neurites grew towards the pulpal explant (the B-pattern) or grew in the opposite direction (the C-pattern). The 3 patterns might reflect actions of different neurite-promoting or -repelling factors.Shortly after entering the mandibular canal, the IAN of the adult rat divides into the mental nerve (MN, 70% of all axons) projecting to muco-cutaneous domains of the chin and the lower lip, and the inferior dental nerve (IDN, 30% of all axons) projecting to the teeth and adjacent tissues. The IAN has achieved the adult number of axons (8,000-10,000) by 1 week. De novo myelination commences at birth and ends by three weeks. In the adult IAN 70% of all axons are myelinated. A mature bimodal size distribution of the myelinated IAN axons has been established by 2 months.During postnatal development, the IAN grows 3x in length, as indicated by the elongation of the mandibular canal. Measurements of the nodal spacing in deveoping and adult IANs shows that the largest intemodes elongate more than the nerve. This mis-match can be explained by the presence of very short internodes (VS!s, L<150 f!m) during the first few postnatal weeks. The VSis reflect a myelin sheath remodelling, through which some proportion of the newly formed internodes are eliminated. In young adult animals VSis are absent, the L/D relation is regular, and the internodes grow in size. During aging, the regular relation between L and D in the IAN breaks down due to reappearance of VSis and the emergence of unusually long intern odes.The sural nerve (SN), which shows little myelin sheath remodelling, and the MN, in which myelin sheath remodelling is frequent, are equally sensitive to K+-channel blockade with 4-aminopyridine (4-AP) during early development. While the adult SN is relatively insensitive to 4-AP, the adult MN remains sensitive. This difference can not be explained in terms of a non-uniform adult nodal structure in the two nerves.The MN component of the IAN exhibits less marked age-related changes than the IDN component. This might be related to the fact that the mucocutaneous targe! of the MN is grossly intact in old rats, while the lower jaw dentition shows marked changes.
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| 24. |
- Josefsson, Martin
(författare)
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Studies on the enantioselective disposition of amlodipine : A challenge in bioanalysis
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To study the disposition of the enantiomers of the calcium channel blocker amlodipine in human plasma, an enantioselective high performance liquid chromatographic (HPLC) assay was developed. Several HPLC techniques such as chiral ion-pair forming, chiral derivatisation and direct separation on chiral columns were evaluated. A robust assay withhigh sensitivity for amlodipine's enantiomers, suitable for large scale analysis of plasma samples, was established by combining enantiomeric separation on Chiral-AGP i.e., an alfa1 acid glycoprotein material, with achiral HPLC using electrochemical detection, in a coupledcolumn system. The enantiomeric separation on the AGP material was evaluated andoptimised by performing chemometric i.e., multivariate analysis. Enantioselective pharmacokinetics, in healthy human subjects, after a single oral dose of amlodipine (Norvasc®) was shown. The pharmacologically active (S)-enantiomer was found in higher plasma concentrations than the (R)-enantiomer in all subjects, but the individual SIR ratios ranged from about 50:50 to 70:30. Comparable inter-individual differences in amlodipine concentration SIR ratio was found in patients during long-term treatment with Norvasc®. However, the changes over time, in the individual subjects, were low and were not significantly influenced if the dose was increased. A difference in systemic blood clearance of the two enantiomers is the most likely cause of the observed difference in pharmacokinetic behavior. At present, however, it cannot be discerned whether this is caused by differences in protein-binding or in intrinsic clearance of the unbound drug. Administration together with grapefruit juice was found to increase the amlodipine plasma concentrations in healthy volunteers without markedly change the plasma concentration SIR ratio. A nonstereoselective inhibition of the first-pass metabolism is proposed. Even though the effects seen were small the clinical significance of this food/drug interaction cannot be totally neglected since there are considerable differences seen between individuals.
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| 25. |
- Kirkegaard Kjølhede, Preben
(författare)
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Burch colposuspension and the pelvic floor
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Burch colposuspension is a surgical method for treatment of stress urinary incontinence, which has become popular due to a high cure-rate. A number of patients, however, develop recurrent urinary incontinence after the colposuspension, or other disabling conditions, such as genital prolapse or voiding difficulties.The study material consists of 243 women with stress urinary incontinence operated on with Burch colposuspension during 1980-88, 57 women with primary stress urinary incontinence assessed during 1991-93, and 16 healthy continent female volunteers.The aims of the study were to investigate the long-term results of the Burch colposuspension, to evaluate the occurrence of genital prolapse and neuropathy in the pelvic floor muscles in relation to the outcome of Burch colposuspension with regard to urinary continence, and to evaluate whether defecography, anorectal manometry and gynecological examination could predict the development of genital prolapse demanding surgery after Burch colposuspension.The study shows that the short-term cure-rate of the Burch colposuspension was high, 95.6%. Median 6 years after the operation 63% were subjectively continent. A further 27% of the women were improved. Prognostic factors for an unsuccessful outcome were immediate and long-tetm voiding difficulties postoperatively, postoperative febrile morbidity, recurrent lower urinary tract infections and previous anti-incontinence operations. After the colposuspension, 15% of the women had been operated on for posterior vaginal wall prolapse.Women, who have recurrent stress urinaty incontinence, seem to have a more pronounced pelvic floor weakness, demonstrated as a higher incidence of rectocele and cystocele, and neurogenic EMG patterns in more muscles in the pelvic floor, than women who are continent after Burch colposuspension.The preoperative gynecological examination, the defecography and the anorectal manometry do not seem to be able to predict the development of genital prolapse demanding surgery after Burch colposuspension.The associations between the occun·ence of genital prolapse and neurogenic EMG patterns, respectively, and the outcome of the Burch colposuspension with respect to continence, demonstrated in the present study, might support the theory that neuromuscular changes in the pelvic floor are contributing factors for the development of recurrent urinary incontinence and genital prolapse after Burch colposuspension. The etiology of recurrent urinary incontinence and urogenital prolapse seems to be multifactorial. Larger prospective studies are however needed to solve the important problems concerning the influence of the neuromuscular function of the pelvic floor on the outcome of anti-incontinence surgery and on the development of genital prolapse.
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| 26. |
- Landtblom, Anne-Marie, 1953-
(författare)
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Epidemiological and radiological aspects of multiple sclerosis
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The first aim of this investigation was to analyse possible risk factors for multiple sclerosis (MS) with focus on animal contacts and occupational exposures, especially to organic solvents. Another aim was to search for specific features in solvent-exposed MS patients mainly by the radiological techniques magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ( 1 H MRS) and also by cerebrospinal fluid (CSF) analysis along with a disability scoring. A further aim was to use 1 H MRS to investigate the metabolite status of brain lesions in the three established clinical subtypes of MS and to analyse for possible differences that may explain their different clinical and pathological characteristics. Finally, the national and countywise distribution of MS in Sweden was investigated during a forty year period by mortality and disability statistics. Both a case-control study and a best evidence synthesis with metaanalyses indicated an about doubled risk of MS from exposure to organic solvents, most clearly demonstrated for the male gender. MRI, 1 H MRS, CSF analyses and disability scoring showed no significant difference between the solvent-exposed and non-exposed MS patients, with one exception. Hypointensity in the basal ganglia, known from other studies of solvent-exposed persons, were overrepresented in the exposed MS patients. There were no differences in metabolite status of MS lesions in relapsing remitting, secondary progressive or primary progressive MS. One MRifl H MRS study showed ringlike appearances and lactate in two MS plaques during relapse, interpreted as oedematous transition forms between acute and chronic lesions. Finally, highly significant geographical variations in MS mortality were found, indicating real fluctuations, as well as a possible increase over time. Vämland county had a constantly high mortality and disability pensioning frequency during forty years and was therefore analysed municipalitywise which revealed a small high risk zone in two northern districts.
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| 27. |
- Larsson, Marie
(författare)
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Dendritic cells from human blood : Antigen handling and expression of adhesion molecules
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dendritic cells are a system of professional antigen-presenting cells that initiate the immune responses. Dendritic cells are widely distributed in the body, both in nonlymphoid tissues, lymphoid tissues and fluids of the body. Dendritic cells arise from the bone marrow and can be classified into interstitial dendritic cells in nonlymphoid tissues, interdigitating dendritic cells in secondary lymphoid tissue, dendritic cells in blnod and veiled cells in lymphatics. They can exhibit differences in each of these compartments that relate to maturation state and microenvironment.Dendritic cells process and present antigens efficiently in situ and stimulate responses from naive and memory T cells in the paracortical area of secondary lymphoid organs. Properties contributing to the dendritic cells' specialized function are the efficiency in clustering T cells and giving the right signals needed to activate naive and resting T cells. The present work was focused on elucidating some key properties of DC biology. The results show that mature human blood dendritic cells express sialyl Lewis x (CD15s), sialyl Lewis a, CD44 and CD77. Adhesion of mature blnod dendritic cells to activated endothelium (human umbilical cord endothelial cells) involves Eselectin. Immature blnod (cytokine-driven) dendritic cells use FcyRII for uptake of IgG immune complexes. Annexin V is involved in antigen trafficking in the endocytotic pathway of soluble proteins in mature blood dendritic cells. Immature blood dendritic cells (cytokine-driven) have the capacity to handle uptake of both soluble and microbial antigens, via fluid-phase pinocytosis, receptor-mediatedendocytosis and phagocytosis. No productive infection of influenza virus and no exogenous ll..-2 is demanded when dendritic cells are used as antigen-presenting cells. Dendritic cells induce cytotoxic T cells even with attenuated influenza A virus.
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| 28. |
- Lindell, Åke
(författare)
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Clinical studies on cystinuria : With special reference to treatment with tiopronin
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cystinuria is an inherited disorder of the renal tubular transport of cystine and the dibasic amino acids across cell membranes. Defective renal tubular reabsorption causes a greatly increased urinary excretion of thepoorly soluble cystine, which in turn results in the formation of renal stones. Because of the life-long tendency for stone formation the patients are highly susceptible to complications of renal stone disease. Urinary supersaturation of cystine can be counteracted by reducing the urinary concentration (increased fluid intake, chemical modification with a sulfhydryl compound) or by increasing its solubility (urinary alkalinization). Long-tenn treatment with the sulfhydryl compound tiopronin (2-mercaptopropionylglycine) was evaluated in 31 patients with homozygous cystinuria (Papers I, II, IV). The patients were followed over an average of 7.8 years and the treatment was monitored by regular measurements of cystine in 24-hour urine samples by ionexch: mge chromatography, and by X-ray examinations. In 40 cystimnic patients total and split kidney function were investigated by gamma camera renography and measurement of glomerular filtration rate (GFR), mainly51CR-EDTA-clearance (Paper Ill). The diurnal variations in urinary cystine excretion was studied in 8 patients (Paper VI), and the effect of a low sodium intake in 13 (Paper V). A urinary free cystine concentration below the assumed level of saturation of 1200 J..Lmol/1 in 24h urine samples was achieved in 90% of patients treated with tiopronin. The required doses varied from 500 to 3000 mg!day which illustrates the necessity for individualization of treatment by regular measurements of the urinary cystine concentration. Increasing doses of tiopronin resulted in an unexpected decrease in the urinary excretion of the soluble tiopronin-cysteine mixed disulphide suggesting an influence on the general metabolism of cystine and cysteine. The rate of new stone· formation wa<> reduced by 60% and the need for active stone removal by 72%. Stone fonnation was eliminated in two thirds of the patients. In the remaining third there was some formation ofrenal stones in spite of acceptable concentrations of cystine in 24h samples. This shows that also the therapeutic level of urinary cystine has to be individually adjusted in some patients. Measurements of cystine in6h samples in patients without tiopronin treatment revealed considerable variations with peak concentration exceeding the corresponding 24h concentration by as mUch as 91%. Fractionated urine sampling may therefore be a tool for further adjustment of therapy. Treatment with tiopronin was well tolerated by the majority of patients, and the finding of clinically reversible membranous glomerulonephritis in 3 patients does not disqualify the drug from further use. Thirty per cent of 40 patients had light to moderate impainnent of renal function. Only 28% had an entirely normal renal function with both GFR and renography within nonnallimits, but there was no case with severe renal impairment. A renographic comparison between the pre-treatment and treatment periods suggested that the stone-preventing treatment based on monitoring of urinary cystine concentration resulted in preservation of renal function. Restriction of sodium intake resulted in a decrease in urinary cystine excretion in patients without tiopronin treatment, whereas the effect was significantly less in patients with tiopronin. In the patients without tiopronin the sodium delivery conveyed by sodium bicarbonate treatment neutralized the increased solubility of cystine obtained by its alkalinizing effect. The excretion of the disulphide between tiopronin and cysteine wasalso sodium dependent suggesting an active tubular reabsorption of this compound.
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| 29. |
- Liu, Shu Ming
(författare)
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Regulation of endothelial transport
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A major role of endothelial cells is to control the influx of solutes into tissues. The aim of the research presented in this thesis was to gain knowledge about the regulation of endothelial transport in relation to the structure of the endothelial cytoskeleton and to elucidate the possible mechanisms of regulation.The transcellular transport of hydrophilic molecules was found to occur viavesicles arranged as chains stretching between the luminal surface and the interior of the cell, and also from the cell interior to the abluminal surface. Intact microtubules were required for this transport, and actin filaments acted as a hinder. In addition, the vesicular transport was stimulated by hydrogen peroxide (H20z) and phorbol myristate acetate (PMA), and the effect of PMA was dependent on reactive oxygen species.The structure of filamentous actin and the permeability were closely associated during stimulation with H20z and PMA. An increase in actin dense peripheral bands (DPBs) was correlated with a decrease in penneability during the first hour of exposure to PMA. For the next 5 h, disruption of DPBs was correlated with an increase in permeability. A low concentration of HzOz (10-5 M) had no effect on either DPBs or permeability, whereas 104 M HzOz disrupted DPBs and increased permeability.Nitric oxide (NO) was involved in the redistribution ofF-actin and the alteration of permeability induced by Hz02 and PMA. Addition of L-arginine, a substrate of NO, increased the number of DPBs and maintained low permeability for up to 6 h in PMAtreated cells. The increase in permeability and disruption of DPBs induced by 10-4 M H202 could be prevented by L-arginine. On the other hand, nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO, disrupted DPBs and caused a direct increase in permeability in PMA-treated cells and in cells treated with both concentrations of Hz02.The involvement of NO in the regulation of endothelial transport by HzOz was cGMP-dependent. An analogue of cGMP, 8-Br-cGMP, prevented the disruption of DPBs and the increase in permeability induced by HzOz even when the production of NO was inhibited by L-NAME.The present findings indicate that the endothelial transport of solutes is associated with the cytoskeleton and that it can be regulated by H20 2 and PMA. The endogenous production of NO appears to be involved in this process via a cGMP-dependent pathway.
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| 30. |
- Ljunghusen, Olof
(författare)
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Leukocyte receptor alternations during systemic inflammatory responses
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The leukocyte adhesion molecule CD llb is very important when granulocytes and monocytes leave the blood stream. This adhesion molecule is stored preformed intracellularly, and can upon stimulation of the cells by, for example, complement split products, be mobilized to the cell surface. CD14 a differentiation antigen and an endotoxin receptor, is found mainly on monocytes, that can be upregulated during stimulation. Upon monocyte CD 14 interactions with endotoxin, pro-inflammatory cytokines like TNF-a. can be produced. The aim of this work was to detect signs of activation of the complement system, leukocyte activation with receptor mobilization and alterations in the plasma levels of soluble selectins, as wen as evidence of cytokineproduction, in model situations of systemic inflammatory responses. For this patients were monitored during the first week after a severe bum damage. We found evidence of complement activation, increased levels of soluble E-selectin as an indication of systemic inflammation, and cytokine production. During surgical revision of burn wounds we detected increased expression of granulocyte CD llb in response to plasma endotoxin liberation, and increased plasma levels of iL-6. In another model situation we studied patients on heart-lung machines undergoing open heart surgery, using heparin-coated or uncoated cardiopulmonary systems. Using uncoated systems, a profound early complement activation was found, leading to rapid mobilization of granulocyte CD llb to the cell surface. We also detected a loss of circulating monocytes during bypass. Neither of these effects were detected when heparin-coated systems were used. Increased monocyte L-selectin expression was found in both groups during bypass, interpreted as a result of redistribution of cells. Plasma levels of soluble L-selectin decreased during early bypass in both groups, probably as a result of dilution of the blood with solutions of the circuit. In the monocyte population, we discovered mobilization of CD 14 during bypass using uncoated systems, but not when coated systems were used. We also found increased plasma endotoxin levels after 5 min of bypass,irrespective of which system was used. Despite the presence of endotoxin, together with increased CD14 expression in the uncoated group, we did not find significant differences between the groups in terms of plasma levels ofTNF-o or IL-6. To conclude, we found rapid alterations in the granulocyte CDllb and monocyte CD14 expression upon stimulation with endotoxin and/or complement products. Monitoring rapid alterations in the activity state ofimportant effector cells in the inflammatory system is thus possible, by studying alterations in their receptor expression.
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