Biomedical subjects

T Sundqvist

Publications and source records attributed to T Sundqvist.

At least 19 recordsLinked to original sources

PubMed2005

Gut microflora associated characteristics in children with celiac disease.

OBJECTIVES: The aim of the study was to investigate the metabolic function of intestinal microflora in children with celiac disease (CD) in order to find out if there is a deviant gut flora in CD patients compared to healthy controls. METHODS: The study group comprised children with CD, consecutively diagnosed according to current criteria given by the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition. Thirty-six children were studied at presentation, i.e., on a normal gluten-containing diet, with clinical symptoms and signs indicative of CD, positive celiac serology markers, and a small bowel biopsy showing severe enteropathy. Forty-seven patients were studied when they had been on a gluten-free diet (GFD) for at least 3 months. For comparison, a group of 42 healthy controls (HC) were studied. The functional status of the intestinal microflora was evaluated by gas-liquid chromatography of short chain fatty acids (SCFAs) in fecal samples. RESULTS: There was a significant difference between untreated CD children and HC as well as between treated CD children and HC regarding acetic, i-butyric, i-valeric acid, and total SCFAs. The propionic and n-valeric acids differed significantly between CD children on GFD and HC. Moreover, there was a strong correlation between i-butyric and i-valeric acids in all study groups. CONCLUSIONS: This is the first study of the SCFA pattern in fecal samples from children with CD. The results indicate that there is a difference in the metabolic activity of intestinal microbial flora in children with CD compared to that in HC. The finding of a different pattern of some SCFAs in celiacs both at presentation and during treatment with GFD indicates that it is a genuine phenomenon of CD not affected by either the diet, the inflammation, or the autoimmune status of the patient.

Biomarkers↗

PubMed2004

Assessment of cartilage thickness utilising reflectance spectroscopy.

A new principle for cartilage layer thickness assessments in joints is presented. It is based on the differences between the absorption spectra of cartilage and subchondral bone (containing blood). High-resolution ultrasound measurements of cartilage thickness were compared with reflection spectroscopy data from the same area of bovine hip joint condyles. A simple mathematical model allowed calculation of thickness and comparison with ultrasound data. The cartilage thickness was changed by being ground in short episodes. For thicker cartilage layers, a high degree of reflection in the 400-600 nm wavelength interval was seen. For thinner cartilage layers, the characteristics of the spectra of blood and bone dominated those of cartilage. The mean (+/- SD) thickness of intact cartilage was 1.21 +/- 0.30 mm (n = 30). In an exponential regression model, spectroscopic estimation of cartilage thickness showed a correlation coefficient of r = 0.69 (n = 182). For thinner cartilage layers (d < 0.5 mm), the mean model error was 0.19 +/- 0.17 mm. Results from a bi-layer Monte Carlo simulation supported the assumption of an exponential relationship between spectroscopy data and reference ultrasound data. The conclusion is that optical reflection spectroscopy can be used for cartilage layer thickness assessment.

Animals↗

PubMed2004

Nitrotyrosine localization to dermal nerves in borderline leprosy.

BACKGROUND: Nerve damage is a common and disabling feature of leprosy, with unclear aetiology. It has been reported that the peroxidizing agents of myelin lipids-nitric oxide (NO) and peroxynitrite-are produced in leprosy skin lesions. OBJECTIVES: To investigate the localization of nitrotyrosine (NT)-a local end-product of peroxynitrite-in leprosy lesions where dermal nerves are affected by a granulomatous reaction. METHODS: We investigated by immunohistochemistry and immunoelectron microscopy the localization of the inducible NO synthase (iNOS) and NT in biopsies exhibiting dermal nerves from patients with untreated leprosy. RESULTS: There were abundant NT-positive and iNOS-positive macrophages in the borderline leprosy granulomas infiltrating peripheral nerves identified by light microscopy, S-100 and neurofilament immunostaining. Immunoelectron microscopy showed NT reactivity in neurofilament aggregates and in the cell wall of Mycobacterium leprae. CONCLUSIONS: Our results suggest that NO and peroxynitrite could be involved in the nerve damage following borderline leprosy.

Granuloma↗

PubMed2004

Local production of nitric oxide in patients with tuberculosis.

Nitric oxide (NO), produced by the inducible nitric oxide synthase (iNOS), is important in host defence against Mycobacterium tuberculosis in rodents, but the presence of high-output NO production in human tuberculosis has been controversial. We investigated iNOS and nitrotyrosine (Ntyr) expression in pleural (n = 7), pulmonary (n = 5) and lymph node biopsies (n = 5) from untreated, newly diagnosed tuberculosis patients. Many iNOS and Ntyr reactive macrophages were observed in granulomas, including Langhans giant cells, indicating high-output NO production at the primary site of disease in tuberculosis.

Biopsy↗

PubMed2003

Altered impedance during pigment aggregation in Xenopus laevis melanophores.

Melanophores are dark-brown pigment cells located in the skin of amphibia, fish and many invertebrates. The skin colour of these organisms is regulated by the translocation of pigment organelles, and the pigment distribution can be altered by external stimuli. The ability to change colour in response to stimuli makes these cells of interest for biosensing applications. It was investigated whether pigment aggregation in Xenopus laevis melanophores can be detected by impedance measurements performed in transparent microvials. The results show that cell attachment, cell spreading and pigment aggregation all resulted in impedance changes, seen particularly at the highest frequency tested (10 kHz). The mechanisms behind the impedance changes were investigated by the addition of latrunculin or melatonin, both of which cause pigment aggregation. The latrunculin-induced aggregation was associated with cell area decrease and filamentous actin (F-actin) breakdown, processes that can influence the impedance. Lack of F-actin breakdown and an increase in cell area during melatonin-induced aggregation suggest that some other intracellular process also contributes to the impedance decrease seen for melatonin. It was shown that impedance measurements reflect not only cell attachment and cell spreading, but also intracellular events.

Animals↗

PubMed2003

Increase in nitric oxide urinary products during gluten challenge in children with coeliac disease.

BACKGROUND: Coeliac disease is a gluten-sensitive enteropathy where pro-inflammatory cytokines and excess nitric oxide (NO) production can contribute to mucosal damage. NO urinary products are elevated in coeliac children on a gluten diet, but it is not known how rapidly this increase develops after gluten exposure. METHODS: Oral gluten challenge was performed in 25 children whose families kept a daily record of gluten intake and symptoms. Blood was analysed monthly for antigliadin (AGA) and endomysium antibodies (EMA). Urine was analysed every second week for NO products, i.e. the sum of nitrite and nitrate was measured with a colorimetric method. We performed a third biopsy when clinical symptoms indicated a relapse. Median age at the post-challenge biopsy was 3.8 (2.7-8.8) years. RESULTS: Signs of morphological or serological relapse were seen in all children. Mean daily gluten intake was 0.10 (range 0.02-0.26) g/kg bodyweight. Median NO level was doubled and significantly higher after 4 weeks of challenge but not after 2 weeks. EMA, but not AGA levels, correlated positively with NO. Intraepithelial lymphocyte count was significantly higher in the post-challenge biopsy, but did not correlate with the NO levels. CONCLUSIONS: NO products in urine increased during gluten challenge. EMA levels reflected severity of mucosal damage, and NO products reflected the inflammatory response, which was doubled after 4 weeks of challenge. The NO analysis is simple and non-traumatic for the child. It can be performed repeatedly during investigation of children with suspected coeliac disease.

Celiac Disease↗

PubMed2003

Arginine as an adjuvant to chemotherapy improves clinical outcome in active tuberculosis.

Nitric oxide (NO) is involved in the host defence against tuberculosis (TB). Patients with TB exhibit increased catabolism and reduced energy intake. Thus the hypothesis for this study was that restoring a relative deficiency in the amino acid arginine, the substrate for mycobactericidal NO production, would improve the clinical outcome of TB by increasing NO production. In a randomised double-blind study, patients with smear-positive TB (n = 120) were given arginine or placebo for 4 weeks in addition to conventional chemotherapy. Primary outcomes were sputum conversion, weight gain, and clinical symptoms after week 8. Secondary outcomes were sedimentation rate and levels of NO metabolites, arginine, citrulline, and tumour necrosis factor-a. Compared with the human immunodeficiency virus (HIV)-/TB+ placebo group, the HIV-/TB+ patients in the arginine group showed significant improvement, defined as increased weight gain, higher sputum conversion rate and faster reduction of symptoms, such as cough. The arginine level increased after week 2 in the HIV-/TB+ arginine group (100.2 microM (range 90.5-109.9) versus 142.1 microM (range 114.1-170.1)) compared with the HIV-/TB+ placebo group (105.5 microM (range 93.7-117.3) versus 95.7 microM (range 82.4-108.9)). HIV seroprevalence was 52.5%. No clinical improvement or increase in serum arginine was detected in arginine supplemented HIV+/TB+ patients compared with placebo. Arginine is beneficial as an adjuvant treatment in human immunodeficiency virus-negative patients with active tuberculosis, most likely mediated by increased production of nitric oxide.

Adult↗

PubMed2002

Inducible nitric oxide synthase is expressed in synovial fluid granulocytes.

The objective of the study was to evaluate the NO-producing potential of synovial fluid (SF) cells. SF from 15 patients with arthritis was compared with blood from the same individuals and with blood from 10 healthy controls. Cellular expression of inducible nitric oxide synthase (iNOS) was analysed by flow cytometry. High-performance liquid chromatography was used to measure l-arginine and l-citrulline. Nitrite and nitrate were measured colourimetrically utilizing the Griess' reaction. Compared to whole blood granulocytes in patients with chronic arthritis, a prominent iNOS expression was observed in SF granulocytes (P < 0.001). A slight, but statistically significant, increase in iNOS expression was also recorded in lymphocytes and monocytes from SF. l-arginine was elevated in SF compared to serum (257 +/- 78 versus 176 +/- 65 micro mol/l, P = 0.008), whereas a slight increase in l-citrulline (33 +/- 11 versus 26 +/- 9 micro mol/l), did not reach statistical significance. Great variations but no significant differences were observed comparing serum and SF levels of nitrite and nitrate, respectively, although the sum of nitrite and nitrate tended to be elevated in SF (19.2 +/- 20.7 versus 8.6 +/- 6.5 micro mol/l, P = 0.054). Synovial fluid leucocytes, in particular granulocytes, express iNOS and may thus contribute to intra-articular NO production in arthritis.

Adult↗

PubMed2001

L-NAME-induced dispersion of melanosomes in melanophores activates PKC, MEK and ERK1.

Melanosome movement represents a good model of cytoskeleton-mediated transport of organelles in eukaryotic cells. We recently observed that inhibiting nitric oxide synthase (NOS) with Nomega-nitro-L-arginine methyl ester (L-NAME) induced dispersion in melanophores pre-aggregated with melatonin. Activation of cyclic adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (PKA) or calcium-dependent protein kinase (PKC) is known to cause dispersion. Also, PKC and NO have been shown to regulate the mitogen/extracellular signal-regulated kinase (MEK)-ERK pathway. Accordingly, our objective was to further characterize the signaling pathway of L-NAME-induced dispersion. We found that the dispersion was decreased by staurosporine and PD98059, which respectively inhibit PKC and MEK, but not by the PKA inhibitor H89. Furthermore, Western blotting revealed that ERK1 kinase was phosphorylated in L-NAME-dispersed melanophores. L-NAME also caused dispersion in latrunculin-B-treated cells, suggesting that this effect is not due to inhibition of the melatonin signaling pathway. Summarizing, we observed that PKC and MEK inhibitors decreased the L-NAME-induced dispersion, which caused phosphorylation of ERK1. Our results also suggest that NO is a negative regulator of phosphorylations that leads to organelle transport.

Animals↗

PubMed2001

Expression of inducible nitric oxide synthase and nitrotyrosine in borderline leprosy lesions.

BACKGROUND: In the response to T-helper cell (Th1)-type cytokines and interactions with pathogens, high levels of nitric oxide (NO) are produced by activated macrophages expressing the inducible NO synthase (iNOS). The role and importance of reactive nitrogen intermediates (RNIs) such as NO and peroxynitrite in the host response to diseases caused by intracellular pathogens such as Mycobacterium leprae and M. tuberculosis is unclear. OBJECTIVES: The aim of this study was to investigate the presence of local production of NO and peroxynitrite in borderline leprosy by using antibodies against iNOS and the product of peroxynitrite, nitrotyrosine (NT). METHODS: We detected the presence of iNOS and NT in skin biopsies from borderline leprosy patients, with and without reversal reaction (RR), by immunohistochemistry (n = 26). RESULTS: In general, the granulomas from borderline leprosy lesions with and without RR showed high and specific expression of iNOS and NT. Moreover, strong immunoreactivity to iNOS and NT was observed in granulomas surrounding and infiltrating dermal nerves. The expression of iNOS and NT was also strong in keratinocytes, fibroblasts and endothelial cells in close relation to the granulomatous reaction. In contrast, normal human skin showed no expression of iNOS and NT in these cells. CONCLUSIONS: We conclude that iNOS and NT are expressed in granulomas from borderline leprosy patients with and without RR and propose that RNIs might be involved in the nerve damage following RR in leprosy.

Biopsy↗

PubMed2000

Nitric oxide regulates the aggregation of stimulated human neutrophils.

Neutrophil aggregation is mediated by both CD18 integrin and L-selectin. Nitric oxide attenuates the integrin-mediated adhesion of neutrophils to collagen and to endothelium and may therefore affect aggregation as well. FMLP-stimulated neutrophils exposed to l-arginine showed increased and prolonged aggregation, whereas cells pretreated with L-NAME did not differ from FMLP-stimulated controls. Nitric oxide is known to induce ADP ribosylation of G-actin, which inhibits polymerization. We detected equivalent levels of total F-actin in cells pretreated with l-arginine or L-NAME and non-pretreated controls. However, neutrophils pretreated with l-arginine and stimulated by CD18 integrin cross-linking exhibited a more limited increase in total F-actin, compared to control and L-NAME-pretreated cells. Thus at least two signaling pathways may be involved FMLP-stimulated aggregation, mediated by CD18 integrins. More specifically, it is plausible that FMLP-receptor signaling upregulates CD18 integrins and endogenous NO subsequently modulates CD18-mediated signaling to prolong aggregation, possibly through ADP-ribosylation of actin.

Actins↗

PubMed2000

Nitric oxide induces dose-dependent CA(2+) transients and causes temporal morphological hyperpolarization in human neutrophils.

We exposed adherent neutrophils to the nitric oxide (NO)-radical donors S-nitroso-N-acetylpenicillamine (SNAP), S-nitrosoglutathione (GSNO), and sodium nitroprusside (SNP) to study the role of NO in morphology and Ca(2+) signaling. Parallel to video imaging of cell morphology and migration in neutrophils, changes in intracellular free Ca(2+) ([Ca(2+)](i)) were assessed by ratio imaging of Fura-2. NO induced a rapid and persistent morphological hyperpolarization followed by migrational arrest that usually lasted throughout the 10-min experiments. Addition of 0.5-800 microM SNAP caused concentration-dependent elevation of [Ca(2+)](i) with an optimal effect at 50 microM. This was probably induced by NO itself, because no change in [Ca(2+)](i) was observed after treatment with NO donor byproducts, i.e. D-penicillamine, glutathione, or potassium cyanide. Increasing doses of SNAP (>/=200 microM) attenuated the Ca(2+) response to the soluble chemotactic stimulus formyl-methionyl-leucyl-phenylalanine (fMLP), and both NO- and fMLP-induced Ca(2+) transients were abolished at 800 microM SNAP or more. In kinetic studies of fluorescently labeled actin cytoskeleton, NO markedly reduced the F-actin content and profoundly increased cell area. Immunoblotting to investigate the formation of nitrotyrosine residues in cells exposed to NO donors did not imply nitrosylation, nor could we mimic the effects of NO with the cell permeant form of cGMP, i.e., 8-Br-cGMP. Hence these processes were probably not the principal NO targets. In summary, NO donors initially increased neutrophil morphological alterations, presumably due to an increase in [Ca(2+)](i), and thereafter inhibited such shape changes. Our observations demonstrate that the effects of NO donors are important for regulation of cellular signaling, i.e., Ca(2+) homeostasis, and also affect cell migration, e.g., through effects on F-actin turnover. Our results are discussed in relation to the complex mechanisms that govern basic cell shape changes, required for migration.

Actins↗

PubMed2000

Nitric oxide modulates intracellular translocation of pigment organelles in Xenopus laevis melanophores.

Pigment organelles in Xenopus laevis melanophores are used by the animal to change skin color, and they provide a good model for studying intracellular organelle transport. Movement of organelles and vesicles along the cytoskeleton is essential for many processes, such as axonal transport, endocytosis, and intercompartmental trafficking. Nitric oxide (NO) is a signaling molecule that plays a role in, among other things, relaxation of blood vessels, sperm motility, and polymerization of actin. Our study focused on the effect NO exerts on cytoskeleton-mediated transport, which has previously received little attention. We found that an inhibitor of NO synthesis, N-nitro-L-arginine methyl ester (L-NAME), reduced the melatonin-induced aggregation of the pigment organelles, melanosomes. Preaggregated melanosomes dispersed after treatment with L-NAME but not after exposure to the inactive stereoisomer (D-NAME) or the substrate for NO synthesis (L-arginine). Signal transduction by NO can be mediated through the activation of soluble guanylate cyclase (sGC), which leads to increased production of cGMP and activation of cGMP-dependent kinases (PKG). We found that both the sGC inhibitor 1H-(1,2,4) oxadiazolo(4,3-a)quinoxalin-1-one (ODQ) and the cGMP analogue 8-bromoguanosine 3':5'-cyclic monophosphate (8-Br-cGMP) reduced melanosome aggregation, whereas the PKG inhibitor KT582 did not. Our results demonstrate that melanosome aggregation depends on synthesis of NO, and NO deprivation causes dispersion. It seems, thus, as if NO and cGMP are essential and can regulate melanosome translocation.

Alkaloids↗

PubMed2000

IgG immune complex binding to and activation of liver cells. An in vitro study with IgG immune complexes, Kupffer cells, sinusoidal endothelial cells and hepatocytes.

BACKGROUND/AIMS: The aim was to study IgG immune complex (IC) binding to isolated hepatocytes, Kupffer cells (KCs) and sinusoidal endothelial cells (SECs). Further, we wished to analyze the capacity of IgG ICs to induce release of reactive oxygen metabolites by the IC-binding liver cells. METHODS: ICs were formed between (125)I-tyramine-cellobiose-labelled dinitrophenyl-conjugated human serum albumin ((125)I-TC-DNP(10)HSA) and polyclonal rabbit IgG antibodies. Binding of ICs to different rat liver cells in suspension was studied at 4 degrees C. Production of reactive oxygen metabolites was measured by luminol-enhanced chemiluminescence at 37 degrees C. RESULTS: IgG mediated binding of (125)I-TC-DNP(10)HSA to both KCs and SECs, but not to hepatocytes. The binding showed saturation kinetics and was blocked by an excess of unlabelled IgG-ICs. IgG-ICs activated KCs, but not SECs, to a chemiluminescence response. CONCLUSIONS: Both KCs and SECs bind IgG-ICs in vitro, probably via Fc receptor interaction. IgG-ICs activate KCs to produce reactive oxygen metabolites. The binding of IgG-ICs to isolated hepatocytes is small.

Animals↗

PubMed2000

High dose prednisolone treatment of leprosy patients undergoing reactions is associated with a rapid decrease in urinary nitric oxide metabolites and clinical improvement.

Evidence is accumulating that nitric oxide (NO) produced by macrophages has a role in the pathogenesis of reactions in leprosy. We followed the urinary levels of the metabolites of NO [nitrite (NO2-) and nitrate (NO3-)] and the clinical response to prednisolone treatment in leprosy patients (n = 9) admitted to ALERT leprosy hospital Addis Ababa, Ethiopia, because of reversal reaction (RR) or erythema nodosum leprosum (ENL). In untreated reactional leprosy patients, the levels of urinary NO metabolites (1645 +/- 454 microM, n = 9, ENL = 4, RR = 5) decreased significantly 2 weeks after high dose prednisolone treatment (1075 +/- 414 microM, P < 0.05), and remained stable 4 (895 +/- 385 microM, P < 0.02) and 6 weeks following treatment initiation (1048 +/- 452 microM, P < 0.02). This decrease was also present when the reactional patients were subdivided according to the type of reaction (ENL, RR) and coincided with a clinical improvement. In patients showing a poor clinical response to steroids, no or minor effects on the urinary NO metabolite levels were observed. We conclude that there is a correlation between the decrease in urinary NO metabolites and a favourable clinical response after high dose prednisolone treatment of reactional leprosy patients.

Adolescent↗

PubMed1999

Mechanical manipulation of bone and cartilage cells with 'optical tweezers'.

The single beam optical gradient trap (optical tweezers) uses a single beam of laser light to non-invasively manipulate microscopic particles. Optical tweezers exerting a force of approximately 7 pN were applied to single bone and cartilage derived cells in culture and changes in intracellular calcium levels were observed using Fluo-3 labelling. Human derived osteoblasts responded to optical tweezers with an immediate increase in [Ca2+]i that was inhibited by the addition of a calcium channel blocker nifedipine. Force applied to different regions of cells resulted in a variable response. [Ca2+]i elevation in response to load was lower in rat femur derived osteoblasts, and not apparent in primary chondrocytes and the osteocytic cell line (MLO Y4).

Calcium↗

PubMed1999

Mechanical manipulation of polymorphonuclear leukocyte plasma membranes with optical tweezers causes influx of extracellular calcium through membrane channels.

Optical tweezers are used mechanically to manipulate the plasma membrane of polymophonuclear leukocytes attached to the bottom of a glass manipulation chamber. The laser trapping beam is dragged across the membrane of cells in calcium-containing and calcium-depleted extracellular medium. This treatment causes a significant rise in the intracellular calcium concentration compared with controls, in cells in calcium-containing medium (239.8 +/- 49.0% against 75.4 +/- 16.4%, respectively), but not in cells in calcium-depleted medium (69.1 +/- 9.6% against 83.4 +/- 18.5%, respectively), indicating that the calcium rise is caused by an influx of calcium from the environment. The rise in calcium concentration is blocked (23.5 +/- 7.1% against 17.1 +/- 4.1%, respectively) by the addition of lansoprazole, indicating that the influx is not due to unspecific membrane damage caused by the mechanical manipulation of the cell. It can therefore be concluded that mechanical manipulation of the neutrophil membrane, in the piconewton force range exerted by the optical tweezer, does not damage the plasma membrane but stimulates a mechanically inducible, membrane channel-mediated influx of extracellular calcium.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed1999

The effects of human burn injury on urinary nitrate excretion.

Different studies have demonstrated both an increase and a decrease in the biosynthesis of nitric oxide (NO) during the first 2 days following experimental and human burn trauma. This study investigated changes in urinary nitrate excretion in humans following thermal injury in order to determine the temporal relationship between NO release and the initial injury. Urinary nitrate was measured in daily 24-h urine collections taken on days 1-7 following burn injury from 15 patients. The control group consisted of 11 healthy, age- and sex-matched patients who kept a nitrate-restricted diet for five days prior to collection of a single 24-h urine sample. The burns group had a mean age of 41.9 +/- 19.4 (mean +/- S.D.) years and a mean total burn surface area (TBSA) of 30.2 +/- 24.9% (mean +/- S.D.). In the burn injured patients, urinary nitrate levels peaked at day 4 and a 2-fold increase relative to day 1 was observed. Urinary nitrate levels were significantly higher in the burns group than the control group on days 4 and 5 only (p < 0.05 for both days). There was no correlation between TBSA and the measured urinary nitrate levels. This study confirms that the biosynthesis of NO is increased during the first week following burn trauma and establishes that the renal elimination of the by-products of NO metabolism is not increased during the first three days after injury. Notwithstanding the potential effects of burns on nitrate distribution, our findings may reflect a delay in the release of NO following the initial insult.

Adolescent↗