Biomedical subjects

P Stierna

Publications and source records attributed to P Stierna.

At least 19 recordsLinked to original sources

PubMed1999

In vivo modulation of glucocorticoid receptor mRNA by inhaled fluticasone propionate in bronchial mucosa and blood lymphocytes in subjects with mild asthma.

BACKGROUND: In vivo regulation of the glucocorticoid receptor (GR) by glucocorticoids provides a means of modulating sensitivity of targeted cells. OBJECTIVE: We sought to determine the in vivo modulation of GR mRNA expression by fluticasone propionate (FP) in subjects with mild asthma. METHODS: Ten atopic asthmatic subjects were treated with FP 250 microg twice daily for 4 weeks. Before and after treatment, the patients underwent fiberoptic bronchoscopy with endobronchial biopsy and sampling of venous blood for measurements of GR mRNA levels. A solution hybridization assay was used for quantitative analysis of GR mRNA. In addition, a 24-hour urinary cortisol excretion and an adrenocorticotropic hormone test before and after treatment with FP were performed. RESULTS: A high interindividual variation in GR mRNA expression was seen. However, we detected a significant reduction of the GR mRNA levels in the endobronchial biopsy specimens after FP treatment (36.6 +/- 23.1 and 25.0 +/- 10.9 amol GR mRNA/microg RNA, respectively; P <.01). In the peripheral blood lymphocytes an even more striking downregulation of the GR by its cognate ligand was documented (30.3 +/- 26.5 and 8.8 +/- 5 amol GR mRNA/microg RNA, respectively; P <.001), possibly reflecting differences in glucocorticoid sensitivity between tissues. A small but significant reduction of the 24-hour urinary cortisol excretion was observed (233 +/- 109 and 157 +/- 66 nmol/L, respectively; P <.01), whereas the feedback regulation of glucocorticoid synthesis by means of the hypothalamic-pituitary-adrenal axis as assessed by the adrenocorticotropic hormone test remained normal after treatment with FP. CONCLUSION: The results in this study confirm the potency of the inhaled corticosteroid FP and provide evidence for a considerable tissue-specific interindividual variation in the expression of the GR.

Adrenocorticotropic Hormone↗

PubMed1999

Microvasculature, blood flow, and vasoreactivity in rabbit sinus mucosa after surgery.

OBJECTIVES: To study the circulatory integrity of the sinus mucosa following surgery, the vascular anatomy, blood flow, and vasoconstrictor response of the regenerated microcirculatory network were analyzed. STUDY DESIGN: Forty-six New Zealand White rabbits were operated on unilaterally with either a modified radical operation (MRO) or middle meatal antrostomy (MMA), using the nonoperated sinus for control purposes. After surgery, the animals were left to heal for 1 month. METHODS: Vascular casts were prepared with a low-viscosity methyl methacrylate resin and studied by scanning electron microscopy. Blood flow was measured by means of radiolabeled microspheres (tin 113 [113Sn]). The vasoconstrictor response to oxymetazoline at increasing concentrations was measured with laser Doppler flowmetry. RESULTS: The number of vessels increased significantly in the regenerated mucosa. The vascular casts displayed a rich microcirculation with local signs of angiogenesis. However, there was no difference in blood flow between the operated cavities and their control sides. Following MRO the regenerated mucosa was more sensitive to the vasoconstrictor effect of oxymetazoline, compared with the control side. This difference was not evident in the MMA-operated sinuses. CONCLUSIONS: In this model, surgery does not seriously interfere with the sinus blood flow, although the regenerated mucosa did display an altered vasoreactivity. These findings should be considered in relation to the effects of surgery intended to limit local inflammation and to ensure the ventilation of the sinuses.

Animals↗

PubMed1999

Experimental nasal intubation: a study of changes in nasoantral mucosa and bacterial flora.

OBJECTIVES: To investigate the local effects in a nasal cavity and its adjacent sinuses of long-term detention of an endonasal tube, with special attention to inflammatory pathology and microbiology. STUDY DESIGN: Experimental rabbit study. METHODS: Four groups of 4 rabbits, in all 16, were unilaterally nasally intubated and evaluated macroscopically, histopathologically, and bacteriologically after 1, 2, 4, and 8 weeks, respectively. RESULTS: At first, in the 1- and 2-week groups to the 4-week group, histopathology, such as degeneration of olfactory mucosa, squamous cell metaplasia, and polyp formations, was observed together with frequent opportunistic bacterial findings in the nasal cavity. Later, in the 4- and 8-week groups, inflammatory mucosal changes, such as septal increase of connective tissue, goblet cell hyperplasia, and epithelial invaginations, were found in the nasal cavity containing a tube. A concomitant increase was found of commensal bacteria adjacent to the tube and the similar bacterial findings in the ipsilateral maxillary sinuses. However, there were no signs of inflammatory reactions in the sinuses. CONCLUSIONS: Our investigation points to the tube as the cause of local goblet cell hyperplasia with an increased mucus production, and as a food source for the commensals with a marked increase of the amount of bacteria. The positive bacterial cultures from the maxillary sinuses might be considered to be colonization. However, because of the possibility of contamination, improved sampling techniques are required, as are further studies.

Animals↗

PubMed1998

The anti-inflammatory effect of fusafungine during experimentally induced rhinosinusitis in the rabbit.

The short-term effects of local intranasal administration of fusafungine were studied for its anti-inflammatory and antimicrobial properties against experimentally induced bacterial rhinosinusitis. The maxillary sinuses of 20 rabbits were infected with encapsulated Streptococcus pneumoniae after mechanical occlusion of each animal's anatomic ostium. Either fusafungine solution or placebo was administered as a nasal spray through the nostrils twice daily for 10 days. Histopathological grading of inflammation, biochemical assay of inflammatory mediators, and the number of bacterial species isolated from the nasal cavities all showed significant recovery from inflammation after fusafungine treatment. The beneficial effects of fusafungine on inflamed sinus mucosa may possibly also be attributable to an initial alleviation of inflammation in the nasal cavity, which permitted entry of the drug to the sinus cavity through a partially reopened ostium. A reciprocal relationship between nasal and sinus reactivity involving generalization of inflammation and recovery was also thought to be of importance. The present findings indicate that local applications of fusafungine may effectively improve clinical conditions producing rhinitis and sinusitis.

Administration, Intranasal↗

PubMed1998

Distribution of Na,K-ATPase is normal in the inner ear of a mouse with a null mutation of the glucocorticoid receptor.

This study was performed in order to test the hypothesis that the glucocorticoid hormone stimulates the formation of Na,K-ATPase in the inner ear of the mouse. An immunohistochemical study with respect to the presence and distribution of glucocorticoid receptors (GR) and Na,K-ATPase in the vestibular and cochlear regions of the inner ear was performed on a C57BL mouse with a null mutation of the glucocorticoid receptor (GR mutant mouse). The wild type C57BL mouse and the CBA mouse served as normal controls. As expected, the homozygous GR mutant mouse showed no specific staining for GR in the inner ear. The heterozygous GR mutant mouse showed faint staining of GR in the spiral limbus, the spiral ganglion, the organ of Corti and the utricle. This staining was markedly less than in the wild type C57BL mouse. Antibody labelling of Na,K-ATPase in the inner ear showed no significant difference between the homozygous and the heterozygous GR mutant mouse as compared to the control wild type C57BL mouse or the CBA mouse. Although earlier studies have shown a positive correlation between levels of glucocorticoid hormone in serum and the concentration of Na,K-ATPase in the inner ear, the hypothesis that glucocorticoid hormones alone stimulate the formation of Na,K-ATPase in the inner ear could not be confirmed by this study. Thus other regulating substances must be considered.

Adrenal Cortex Hormones↗

PubMed1998

Changes in glycoconjugate expression of the sinus mucosa during experimental sinusitis: a lectin histochemical study of the epithelium and goblet cell development.

Lectin expression in both normal and inflamed sinus mucosa in rabbit was investigated histochemically. A different staining pattern was observed in the inflamed mucosa, i.e. the degree of staining reactivity with Canavalia ensiformis (ConA) decreased, whereas staining with Ulex europaeus agglutinin-I (UEA-I), Arachis hypoga (PNA) with neuraminidase pretreatment and Triticum vulgaris (WGA) intensified, indicating an enhanced fucosylation as well as sialylation. Goblet cells were stained with UEA-I, WGA, PNA and PNA with neuraminidase pretreatment, but scarcely with ConA. Positive PNA staining of basal cells and epithelial secretory granules was observed in the inflamed mucosa, especially close to areas where goblet cell development was prolific. It was therefore assumed that basal cells can differentiate into goblet cells-through epithelial secretory cells accompanied by sialylation and/or sulphonation of their mucins. It is concluded that the changes in glycoconjugate expression as well as goblet cell development in the inflamed mucosa are of importance for both local host resistance and defence mechanisms against microorganisms during the early stages of the inflammatory process.

Animals↗

PubMed1998

Early stages in the development of goblet cells in the paranasal sinuses: a multimethodological study in the rabbit.

To evaluate the pattern of goblet cell differentiation in sinus mucosa in response to external stimuli, New Zealand White rabbits were subjected to either experimental sinusitis or topical capsalcin application. Sinus mucosa was examined by light microscopy after serial sectioning, whole-mount preparation or immunohistochemistry. The mucosa was also examined by electron microscopy after perfusion fixation or high-pressure freezing. While goblet cells were normally very scarce in the healthy rabbit maxillary sinus mucosa, such cells were frequent after experimental sinusitis or topical capsaicin application. The process of goblet cell differentiation seems to follow a sequential path where serous secretory cells start to produce an increasing amount of mucous granules which appear electron lucent after conventional fixation. Parallel to this shift in secretion production, the cell assumes a bulging appearance after conventional fixation. It is concluded that newly formed goblet cells are recruited from intermediate secretory cell stages rather than from ciliated cells.

Administration, Topical↗

PubMed1998

Effect of systemic pretreatment with betamethasone on the bacterial flora, inflammatory response, and polyp formation in experimentally infected rabbit maxillary sinus mucosa.

To investigate possible effects of corticosteroids on polyp formation and local bacterial colonization, pneumococcal sinusitis was experimentally induced in rabbits pretreated with betamethasone or saline. After 7 days, macroscopic polyps were counted post-mortem and on histologic slides after serial sectioning. Histologic sections were also examined with light microscopy. Macroscopic polyps were significantly fewer in animals given betamethasone, while there was no difference regarding the number of microscopic polyps. Ingrowth of pathogenic microorganisms was found in five of eight rabbits given placebo but in none of the animals treated with corticosteroids (P < 0.05). The reduced number of pathogenic strains in these animals may be explained by a better-preserved local host defense. The lower number of macroscopic polyps in the same animals could be because of a delayed mucosal repair and subsequent polyp formation.

Animals↗

PubMed1998

Effects of surgery on mucosal pathologic changes following experimental sinusitis in rabbit.

In the present investigation, the regenerative capacity of the infected maxillary sinus mucosa following surgical procedures was studied in a rabbit model. Sinusitis was induced by occluding the ostium with and without the addition of Staphylococcus aureus or Bacteroides fragilis, or by provoking a prolonged bacterial infection with both pathogens. The surgical procedures performed were 1) widening of the natural sinus ostium (middle meatal antrostomy; MMA) and 2) removal of sinus mucosa without ostial interference (modified radical operation; MRO). The histologic features of the entire nose-sinus complex were studied, graded semiquantitatively, and compared with findings in untreated sinusitis, or after surgery only. Whereas MMA and MRO both led to a decrease of the inflammatory features of the sinus mucosa in induced sinusitis, persistent local histopathology was observed in the ostial region following MMA surgery. This indicates the importance of local pathologic changes resulting from interactions of bacterial colonization, inflammation, and surgery in chronic sinusitis.

Animals↗

PubMed1998

Variations in glucocorticoid levels within the physiological range affect plasma leptin levels.

OBJECTIVE: Leptin, the obese gene product, is thought to regulate body fat through its action on hypothalamic receptors that influence satiety. The hormonal regulation of leptin is important, since it might affect adiposity. Leptin regulation in man is poorly understood. We studied the relation between endogenous cortisol and leptin levels as well as the acute and chronic effects of a low dose of dexamethasone (DEX) on plasma leptin levels in healthy male volunteers. SUBJECTS AND EXPERIMENTAL PROTOCOL: The correlation between basal plasma levels of leptin and cortisol and the chronic effect of DEX treatment were studied in 12 subjects. Plasma leptin and cortisol levels were determined every other hour for 24 h, before and after 2 weeks of oral administration of 0.1 mg DEX twice daily. The acute effect was studied in 20 subjects, who received 1 mg DEX at 2300 h. Fasting blood samples were taken at 0800 h on the same day (i.e. before DEX) and on the day after. RESULTS: Under basal conditions, we found a correlation between mean plasma levels of leptin and cortisol (r = 0.7, P<0.02). Mean plasma leptin levels had increased by 50% after 2 weeks of DEX treatment (P<0.05). The circadian rhythm of leptin was preserved, but the night peak occurred 2.5 h earlier (P<0.05). Fasting plasma leptin levels were 20% higher 9 h after 1 mg DEX orally than at the same time on the day before (P<0.002). CONCLUSION: Physiological variations in cortisol are involved in the regulation of leptin.

Adult↗

PubMed1997

Evidence that the beta-isoform of the human glucocorticoid receptor does not act as a physiologically significant repressor.

Alternative splicing of the human glucocorticoid receptor (hGR) primary transcript generates two receptor isoforms, hGRalpha and hGRbeta, with different carboxyl termini diverging at amino acid 727. By reverse transcriptase-polymerase chain reactions it was previously demonstrated that the hGRbeta message had a widespread tissue distribution. To demonstrate the presence of hGRbeta as protein we produced specific rabbit antisera to hGRbeta, as well as a hGRbeta-specific mouse monoclonal IgM antibody, by peptide immunizations. By SDS-polyacrylamide gel electrophoresis and Western immunoblotting we showed that hGRbeta is endogenously expressed at the protein level in HeLa cells and human lymphatic leukemia cells. Using an antibody directed against an epitope shared by both isoforms we showed a relatively lower expression of the hGRbeta form. We also showed that hGRbeta bound to hsp90 by immunoprecipitation of in vitro translated hGRbeta in reticulocyte lysate with hsp90-specific antibodies, a coprecipitation occurring also in the presence of dexamethasone. We could not demonstrate that hGRbeta inhibited the effects of dexamethasone-activated hGRalpha on a glucocorticoid-responsive reporter gene. In conclusion, low hGRbeta expression levels and hGRbeta-hsp90 interaction maintained in the presence of ligand and lack of inhibition of hormone-activated hGRalpha effects challenge the concept of the hGRbeta isoform as a proposed dominant negative inhibitor of hGRalpha activity.

Alternative Splicing↗

PubMed1997

Effects of experimental Mycoplasma pulmonis infection on sensory neuropeptides and airway mucosa in the rat.

The effect of airway infection on neurogenic inflammation is not known. The present study examines the effect of Mycoplasma pulmonis infection on the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) in the trigeminal ganglion and in the mucosa of the nose and trachea in rats. We compared germ-free (GF), conventionally raised (CV) and specific pathogen-free (SPF) rats. The concentrations of SP and CGRP in the nasal mucosa were assessed with immunohistochemistry, and their prohormonal transcripts in the trigeminal ganglion were assessed with Northern blot. Mucosa was also processed for light microscopy and electron microscopy. SP-like immunoreactivity was greater in the nasal mucosa of infected animals than in uninfected controls. CGRP-like immunoreactivity was greater in the nasal septum, but not in the nasal turbinate, of infected than uninfected animals. In contrast, no change was evident in the expression levels of the prohormonal transcripts in the trigeminal ganglion. Infected nasal and tracheal mucosa was oedematous and locally infiltrated with inflammatory cells. In the nose of uninfected GF rats, subepithelial lymphoid aggregations were scarce and appeared inactive. We conclude that Mycoplasma pulmonis infection results in increased immunoreactivity of substance P, probably within nerves. There was no clear evidence of increased synthesis of the precursors of substance P and calcitonin gene-related peptide.

Animals↗

PubMed1997

Circadian cortisol rhythms in healthy boys and girls: relationship with age, growth, body composition, and pubertal development.

To provide basic information on the normal functioning of the hypothalamus-pituitary-adrenal axis in relation to pubertal development, growth (weight and height), body composition, and gender and to obtain reference data for serum cortisol concentrations in children, we investigated the basal circadian rhythm of serum cortisol in a group of 235 healthy children (162 boys and 73 girls). The age range was between 2.2-18.5 yr. Serum cortisol was analyzed from venous blood samples taken at 1400, 1800, 2200, 0200, 0400, 0600, and 1000 h. No evidence was found for differences in temporal placement or level of the circadian cortisol rhythm in relation to age, growth, or body composition. However, we found a broad range of cortisol levels in a healthy population, with individual mean diurnal levels ranging from 100-510 nmol/L. Regardless of high or low mean diurnal cortisol levels, repeated measurements within and between pubertal stages indicated that an individual remains in his or her cortisol range throughout pubertal development. In conclusion, the present study shows that 1) serum cortisol levels do not correlate with either age or gender; 2) there is a large and significant interindividual variability in endogenous mean diurnal cortisol levels; and 3) despite this variability between individuals, there is no correlation between cortisol levels and either body composition or growth rate. This suggests that the variability in cortisol levels is an expression of normal homeostasis rather than pathology.

Adolescent↗

PubMed1997

Ciliary ultrastructure in experimental sinusitis.

Ultrastructure of respiratory cilia was observed in experimental sinusitis of rabbit maxillary sinuses. Sinus mucosa of 15 rabbits was inoculated with Streptococcus pneumonia bacteria and of 16 rabbits with Bacteroides fragilis bacteria. Specimens were taken during 12 weeks' observation time and they were studied by transmission electron microscopy from the cross-sections. A special emphasis was paid to the number of cilia, the ciliary orientation, the tubular anomalies, the presence of dynein arms and the compound cilia. It seems likely that pneumococcal sinusitis is a more toxic infection to the epithelium causing loss of ciliated cells and cilia than B. fragilis infection. In anaerobic infection ciliary ultrastructure remains normal and dynein arms as well as normal tubular ultrastructure were seen even after 12 weeks' infection.

Animals↗

PubMed1996

A comparison of morphological effects on the rabbit nasal and sinus mucosa after surgical denervation and topical capsaicin application.

In order to study morphological effects on the nasal and sinus mucosa, New Zealand White rabbits underwent either unselective, regional sectioning of sensory and parasympathetic nerve branches or topical treatment of the mucosa with capsaicin. Ten days after treatment, mucosal specimens were analyzed by light and electron microscopy. Immunohistochemistry was used to evaluate neuropeptides present, in particular substance P, calcitonin gene-related peptide, vasoactive intestinal peptide and neuropeptide Y. In surgically denervated rabbits, mucosal glands were found to be enlarged and contained an increased number of zymogen granules having a bipartite substructure. Topical capsaicin application caused localized epithelial changes in the sinus mucosa and maxilloturbinal region of the nose, including clotting of cilia and an increased number of goblet cells. Reduced amounts of all neuropeptides investigated were found in the surgically denervated animals, while topical capsaicin treatment had only marginal effects on the mucosal neuropeptide content. The morphological changes observed after surgical denervation suggest an imbalance between neural stimulation and secretory capacity of the mucosal glands. These findings could explain the difference in clinical effect noted between sectioning of the vidian nerve and topical treatment with capsaicin in patients with perennial rhinitis.

Administration, Topical↗

PubMed1996

Regulation of glucocorticoid receptor mRNA in nasal mucosa by local administration of fluticasone and budesonide.

The glucocorticoid receptor (GR) is downregulated by glucocorticoids (autoregulation). In contrast, the metallothionein gene (MTIIa) is positively regulated by glucocorticoids, which requires a functional receptor protein. We have investigated the expression of GR and MTIIa mRNA in nasal mucosal biopsy specimens, nasal brush-lavage samples, and peripheral blood lymphocytes from 14 healthy volunteers after local treatment with one of two different glucocorticoids: fluticasone propionate or budesonide. In nasal mucosal biopsy specimens, a significant decrease in GR mRNA occurred with increasing doses of both steroids, whereas a significant and parallel increase in MTIIa mRNA was observed. We found nasal brush-lavage less suitable for studies of GR mRNA and MTIIa mRNA regulation by locally administered glucocorticoids. In mucosal biopsy specimens, but not in peripheral blood lymphocytes, we found a correlation between basal GR mRNA and MTIIa mRNA levels, where low GR mRNA levels were associated with low MTIIa mRNA levels, and vice versa. In conclusion, this study shows that locally administered glucocorticoids significantly affect the expression of specific genes and that there is an interindividual and tissue-specific variation in GR mRNA and MTIIa mRNA expression, which may be used in studies of variations in clinical responses to nasal glucocorticoids.

Administration, Topical↗

PubMed1996

Glucocorticoid resistant syndromes--molecular basis and clinical presentations.

The mechanisms of action of glucocorticoid hormones are mediated via specific intracellular receptor proteins. The glucocorticoid receptor (GR) regulates expression of specific target genes or gene networks by ligand-dependent transcriptional activation, i.e. ligand-dependent activation of the receptor with subsequent dimer formation and DNA binding. There are a number of factors, such as the receptor concentration, receptor associated proteins, receptor alterations and the effects on the gene network including hormonal regulation of transcription, mRNA splicing and translation, that might influence glucocorticoid responsiveness in a normal and healthy population as well as in different diseases. Several categories of glucocorticoid resistance have been described including inherited GR resistance which has been explained in terms of specific mutations and offers an important model for genetic and clinical studies of steroid sensitivity, and relative glucocorticoid resistance, which occurs naturally in the course of cellular differentiation, cell to cell or tissue to tissue, since all cells possess receptors for glucocorticoids but do not show the same response to them. From a clinical point of view, it is also interesting to consider preexisting genetic susceptibility to glucocorticoids, acquired changes in the GR gene structure and organization, including alterations of noncoding sequences, and the importance of mutations, deletions and other changes in the GR gene affecting receptor function. Analysis of mutations within the receptor resulting in relative glucocorticoid resistance, both generalized inherited glucocorticoid resistance (GIGR) and directed mutagenesis, has identified two regions of clustered mutations in the proximity of previously identified affinity labeled residues directly affecting the steroid binding function. Finally, studies of New Words primates and cell lines derived from hematologic malignancies constitute animal and human models for the molecular basis of glucocorticoid resistance where a number of inherited and acquired mutations in the GR gene have been demonstrated.

Animals↗

PubMed1996

Experimentally induced polyps in the sinus mucosa: a structural analysis of the initial stages.

To document polyp formation in the sinus mucosa, the authors of this study subjected New Zealand white rabbits to different modes of manipulation intended to induce inflammation of the maxillary sinus. These manipulations included a combination of bacterial infection and mechanical trauma, the deposition of agarose into the sinus cavity, and the deposition of N-formyl-methionyl-leucyl-phenylalanine, a chemotactic peptide, into the sinus cavity. A majority of animals developed polyps, which were examined by light and electron microscopy. Polyp formation appears to involve epithelial disruption and the migration of immature branching epithelium. While part of the migrating epithelium eventually covers the mucosal defect, other branches spread into the underlying connective tissue, where intraepithelial microcavities with a differentiated, ciliated lining are formed. Fusing cavities separate the developing polyp body from the adjacent mucosa. With the described method, mucosal polyps can be induced with high reproducibility.

Animals↗