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Thomas Horn

Publications and source records attributed to Thomas Horn.

36 records · Page 2Linked to original sources
PubMed2003

Small vulvar squamous cell carcinomas and adjacent tissues. A morphologic study.

Vulvar squamous cell carcinomas are of different subtypes and degrees of differentiation, and may be associated with adjacent lichen sclerosus and/or varying degrees of dysplasia. The aim of this investigation was to study small carcinomas with a diameter of less than 2 cm in order to find a possible relation between subtypes of carcinomas and adjacent epithelial changes. Fourteen cases of small vulvar squamous cell carcinomas were totally embedded in paraffin. Serial sectioning made a detailed mapping of all different lesions possible, and a two- and three-dimensional imaging was obtained in each case. Seven patients with keratinizing squamous cell carcinomas (median age 65) had adjacent lichen sclerosus. All carcinomas were completely surrounded by areas of VIN1. VIN2 and VIN3 were not found. Seven patients without lichen sclerosus (median age 58) showed squamous cell carcinomas of the keratinizing type (n=2) or the basaloid type (n=5). Five of these cases were incompletely surrounded by varying degrees of dysplasia, mainly VIN2 and VIN3. Two different pathogenetic pathways for the development of vulvar squamous cell carcinoma are likely.

Adult↗
PubMed2003

Selective lack of the C16:0 fatty acid isoform of sulfatide in pancreas of type II diabetic animal models.

Sulfatide (3'-sulfogalactosyl-ceramide) is a glycosphingolipid mainly located in the nervous system, but has also been found in the islets of Langerhans. Previous studies have suggested that sulfatide is involved in insulin processing and secretion. In this study, sulfatide expression and metabolism in pancreas and isolated islets of the type II diabetes models, ob/ob- and db/db mouse, was investigated using TLC-ELISA, metabolic labelling and electron microscopy. As in non-diabetic Lewis rat and human pancreas, sulfatide was located in secretory granules of the beta cells. However, the type II diabetic animal models and their background strains had an altered sulfatide expression, involving the lack of the C16:0 sulfatide fatty acid isoform, compared to non-diabetic Lewis rat, BALB/c mouse and human pancreatic tissue, in which the two dominating pancreatic sulfatide isoforms C16:0 and C24:0 are expressed. Correspondingly, in isolated ob/ob islets, sulfatide synthesis excluded the production of C16:0 sulfatide. Insulin administration to ob/ob mouse, which lowers beta cell activity, resulted in significantly increased sulfatide expression in pancreas (p=0.0003), but still no expression of the C16:0 sulfatide isoform. In vitro, the C16:0 sulfatide was shown to be the isomer involved in the preservation of insulin crystals. Thus, it is hypothesized that the selection of sulfatide isomers in pancreas might be a genetic factor contributing to disease development in type II diabetic animal models.

Animals↗
PubMed2003

Expression of stratum corneum chymotryptic enzyme in ichthyoses and squamoproliferative processes.

OBJECTIVE: Stratum corneum chymotryptic enzyme (SCCE) is a serine protease, which is thought to play a role in the desquamation of skin via the proteolysis of desmosomes in the stratum corneum. The objective of this study was to investigate the expression of SCCE in ichthyoses and squamoproliferative processes, conditions in which the shedding and replacement of epidermal cells is disrupted. DESIGN: Tissue samples from cases of Netherton's syndrome, congenital ichthyosiform erythroderma, ichthyosis vulgaris, actinic keratosis, squamous cell carcinoma in situ, and invasive squamous cell carcinoma were examined for expression of SCCE using immunohistochemistry. MAIN OUTCOME MEASURES: The slides were qualitatively analyzed for the expression of SCCE by a certified dermatopathologist. RESULTS: In all disease states, we found that the expression of SCCE was absent in areas of parakeratotic stratum corneum of normal thickness. In areas of mixed orthokeratosis and parakeratosis where the stratum corneum was greatly thickened as might correspond clinically to a cutaneous horn, SCCE staining was either absent or focally aggregated without regard to orthokeratosis or parakeratosis. Of note, complete absence of SCCE expression was not observed in any of the cases of ichthyosis examined, nor was there increased expression of SCCE in the atypical cells of the squamoproliferative disorders. CONCLUSIONS: These results suggest that SCCE is abnormally expressed in skin where epidermal cell kinetics are disrupted due to inherited and acquired defects. Further investigation is needed to determine causality between the abnormal expression of SCCE and the altered cell kinetics in these diseases.

Carcinoma in Situ↗
PubMed2003

The detrusor muscle cell in bladder outlet obstruction--ultrastructural and morphometric findings.

OBJECTIVE: Lower urinary tract symptoms (LUTS) in elderly males are not solely caused by bladder outlet obstruction (BOO) and may be at least partly attributable to detrusor dysfunction. Urodynamically, patients may show instability, hypocontractility, BOO or combinations of these findings. These findings have been related to specific ultrastructural changes in detrusor smooth muscle cells; however, this relationship is controversial. The aim of this study was to correlate ultrastructural findings in patients with BOO with urodynamic parameters. MATERIAL AND METHODS: In 25 men with BOO verified by means of a full urodynamic evaluation, including a pressure-flow study, a detrusor biopsy was obtained. Six men without BOO served as controls. Biopsies for electron microscopy were analysed semiquantitatively and morphometrically to determine the presence of muscle cell hypertrophy, variation in intercellular distances, occurrence of abnormal cell junctions and configurations and intracellular changes. RESULTS: The only parameter which was found to relate to the degree of obstruction in BOO was an increase in intra- and interfascicular elastin, all other correlations not reaching significance. CONCLUSION: This study does not confirm a specific relationship between ultrastructural detrusor smooth muscle features and various types of BOO. Therefore ultrastructural investigation of detrusor smooth muscle cells cannot replace urodynamic evaluation in the classification of LUTS.

Adult↗
PubMed2003

The cysteinyl-leukotriene D4 induces cytosolic Ca2+ elevation and contraction of the human detrusor muscle.

PURPOSE: The role of intracellular Ca2+ in the activation of human detrusor smooth muscle cells (SMCs) is pivotal. Recently we showed that the mast cell derived pro-inflammatory mediator leukotriene D(4) (LTD(4)) induces increase in intracellular free Ca2+ ([Ca2+](i)) in human detrusor myocytes. In the current study we examined the mechanisms underlying LTD(4) induced increase in [Ca2+](i) and tested whether LTD(4) induces muscle contraction by measuring force development in human detrusor tissue. MATERIALS AND METHODS: Cultures of human detrusor SMCs were obtained from patients with benign bladder diseases undergoing cystoscopy. [Ca2+](i) was measured in fura-2 loaded SMCs using micro-spectrofluorometry and dynamic video imaging. Contractile force was monitored with an especially built mini-myograph. RESULTS: Spontaneous oscillations in [Ca2+](i) and force were observed. In the absence of calcium these oscillations were absent. LTD(4) caused a concentration dependent increase in [Ca2+](i) and isometric force. Calcium was released exclusively from intracellular stores. Increases in [Ca2+](i) and force were inhibited in dose dependent fashion by the LTD(4) receptor antagonists montelukast and zafirlukast. Likewise, LTC(4) and LTE(4) induced an increase in [Ca2+](i) and contractile force in the rank order LTD(4) >LTC(4) >LTE(4). Inhibition of Ca2+ induced Ca2+ release (CICR) with thapsigargin and ryanodine suggested the presence of a functional CICR in SMCs. CONCLUSIONS: To our knowledge this study demonstrates for the first time that the cysteinyl-leukotriene LTD(4) induces contraction in human detrusor SMCs. LTD(4) induced force and increased [Ca2+](i) were entirely dependent on Ca2+ release from intracellular stores. The action of LTD(4) on force development and increased [Ca2+](i) appeared to be specific, mediated by the binding and activation of specific LTD(4) receptors on SMCs. Also, to our knowledge this report is the first to show that human detrusor SMCs are sensitive to ryanodine, consistent with the hypothesis that a CICR is present and functional in these cells. The presence and role of endogenous cysteinyl leukotrienes for normal contractile functioning of the human detrusor during inflammation remains to be elucidated.

Acetates↗
PubMed2003

Simple and efficient method for isolation and cultivation of endoscopically obtained human colonocytes.

Few comparative and validated reports exist on the isolation and growth of colonoscopically obtained colonic epithelium. The aim of this study was to develop and validate a simple method for the cultivation of colonoscopically obtained colonocytes. Forty patients, who underwent routine colonoscopy and where the diagnosis of irritable bowel syndrome was later reached, were included. Seven colon biopsies were taken and incubated at varying time periods of 10-120 min and temperatures of 4-37 degrees C in a chelating buffer. The epithelium was then harvested and cultivated under three different conditions: 1) on a collagen coating, 2) embedded in a collagen gel, or 3) embedded in a gel put on a porous well insert. The effect of conditioned medium (CM), insulin, transferrin, selenium, and the oxygen content was assessed. Viability was tested by the metabolic dimethylthiazol-diphenyl-tetrazolium bromide assay, by flowcytometry, by phase contrast microscopy, and by transmission electron microscopy. Incubation at 21 degrees C for 75 min gave an optimal yield of 3 x 10(6) (2.0-3.8 x 10(6)) viable epithelial cells in intact crypts per seven biopsies. Embedding of crypts in a collagen gel put on a porous membrane was superior to the other methods applied [P < 0.003; median viability 71% (62-100%) compared with preculture values] after 24 h, which was a 160% increase in viability compared with coat-cultivated cells. CM had similar viability supporting effects to FCS. Other supplements had no effects. A simple method is presented, which makes cultivation of colonocytes obtained at endoscopy possible for up to 72 h.

Cell Culture Techniques↗
PubMed2003

Serum cystatin C reflects glomerular endotheliosis in normal, hypertensive and pre-eclamptic pregnancies.

OBJECTIVE: To study the correlation between serum cystatin C levels and renal structural changes in normal, hypertensive and pre-eclamptic pregnancy to evaluate it as a marker of the degree of renal involvement in pre-eclampsia. DESIGN: An observational prospective study. SETTING: University Hospital of Lund, Sweden. SAMPLE: Thirty-six women with hypertensive disease in pregnancy and 12 healthy pregnant women in the third trimester recruited from maternal health care centres in the catchment area of the hospital. METHODS: Renal biopsy samples were obtained from all participants and the degree of endotheliosis as well as the mean glomerular volume was evaluated by light microscopy in silver methenamin-stained sections. Serum cystatin C levels were measured and correlated to the structural changes. MAIN OUTCOME MEASURES: Correlation among degree of glomerular endotheliosis, glomerular volume and serum cystatin C. RESULTS: Serum cystatin C levels differed between the different degrees of endotheliosis, showing a highly significant increasing linear trend. They also correlated significantly with glomerular volume (r = 0.60, P < 0.001). Mean serum urate and creatinine levels also increased with the degree of endotheliosis, but not above the reference interval for normal term pregnancy, even in pre-eclamptic women. CONCLUSION: Serum cystatin C may be used as a marker, not only for impaired renal function, but also for the degree of glomerular endotheliosis and increase in glomerular volume in pregnancy. It may be of value in the monitoring of pregnancies complicated by pre-eclampsia.

Adult↗
PubMed2003

Glomerular endotheliosis in normal pregnancy and pre-eclampsia.

OBJECTIVE: To investigate the proportion of women with findings characteristic for pre-eclampsia, as opposed to renal disease, in a controlled study of hypertensive pregnant women undergoing antepartum renal biopsy. DESIGN: An observational prospective controlled study. SETTING: University Hospital of Lund, Sweden. SAMPLE: Thirty-six previously healthy women with hypertensive disease in pregnancy, consecutively admitted to the antenatal ward at onset of disease during a 20 month period and giving informed consent, as well as 12 voluntary healthy pregnant controls. METHODS: Renal biopsy samples were obtained from all participants and evaluated by light microscopy, electron microscopy and immunofluorescence techniques. MAIN OUTCOME MEASURES: Presence and degree of glomerular endotheliosis. RESULTS: Glomerular endotheliosis was present in all women with pre-eclampsia and gestational hypertension, and in 5 of the 12 controls, although significant differences in the degree of endotheliosis were found between the groups. Clinically undetected renal disease was not diagnosed in any of the women. CONCLUSION: Glomerular endotheliosis was found in women with normal pregnancy as well as in both non-proteinuric and proteinuric hypertension and is consequently not, as earlier believed, pathognomonic for pre-eclampsia. The transition between normal term pregnancy, gestational hypertension and pre-eclampsia appears to be a continuous process, perhaps of increasing adaptation to pregnancy. Pre-eclampsia may be the extreme of the adaptational process, rather than a separate abnormal condition. Clinically undetected renal disease could be a rare cause of hypertension in pregnancy.

Adult↗
PubMed2002

Use of peptide antibodies to probe for the mitoxantrone resistance-associated protein MXR/BCRP/ABCP/ABCG2.

Recent studies have characterized the ABC half-transporter associated with mitoxantrone resistance in human cancer cell lines. Encoded by the ABCG2 gene, overexpression confers resistance to camptothecins, as well as to mitoxantrone. We developed four polyclonal antibodies against peptides corresponding to four different epitopes on the mitoxantrone resistance-associated protein, ABCG2. Three epitopes localized on the cytoplasmic region of ABCG2 gave rise to high-affinity antibodies, which were demonstrated to be specific for ABCG2. Western blot analysis of cells with high levels of ABCG2 showed a single major band of the expected 72-kDa molecular size of ABCG2 under denaturing conditions. Immunoblot analysis performed under non-reducing conditions and after treatment with cross-linking reagents demonstrated a molecular weight shift from 72 kDa to several bands of 180 kDa and higher molecular weight, suggesting detection of dimerization products of ABCG2. Evidence of N-linked glycosylation was also obtained using tunicamycin and N-glycosidase F. Finally, both by light, fluorescence and electron microscopic immunohistochemical staining, we demonstrate cytoplasmic and predominantly plasma membrane localization of ABCG2 in cell lines with high levels of expression. Plasma membrane staining was observed on the surface of the chorionic villi in placenta. These results support the hypothesis that ABCG2 is an ABC half-transporter that forms dimers in the plasma membrane, functioning as an ATP-dependent outward pump for substrate transport.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2002

Sulfatide is associated with insulin granules and located to microdomains of a cultured beta cell line.

Previous studies using pancreas from various mammals and freshly isolated islets from rat pancreas have provided evidence supporting possible involvement of the glycosphingolipid sulfatide in insulin processing and secretion. In this study, sulfatide expression and metabolism in the beta cell line RINr1046-38 (RIN-38), commonly used as a model for beta cell functional studies, were investigated and compared with previous findings from freshly isolated islets. RIN-38 cells expressed similar amounts (2.7 +/- 1.1 nmol/mg protein, n = 19) of sulfatide as isolated rat islets and also followed the same metabolic pathway, mainly through recycling. Moreover, in agreement with findings in isolated islets, the major species of sulfatide isolated from RIN-38 cells contained C16:0 and C24:0 fatty acids. By applying subcellular isolations and electron microscopy and immunocytochemistry techniques, sulfatide was shown to be located to the secretory granules, the plasma membrane and enriched in detergent insoluble microdomains. In the electron microscopy studies, Sulph I staining was also associated with mitochondria and villi structures. In conclusion, RIN-38 cells might be an appropriate model, as a complement to isolated islets where the amount of material often limits the experiments, to further explore the role of sulfatide in insulin secretion and signal transduction of beta cells.

Animals↗
PubMed2002

The histopathology of folliculitis in HIV-infected patients.

BACKGROUND: Cutaneous disease referable to human immunodeficiency virus (HIV) infection has become less common with the advent of widespread administration of antiretroviral medications, particularly the protease inhibitors. Pruritic eruptions that fall into the general categorization of folliculitis continue to be problematic. METHODS: In this report, we describe 33 skin biopsy samples prospectively obtained of follicular papules and pustules from 33 HIV-infected individuals with the clinical diagnosis of HIV-related folliculitis. RESULTS: The histopathologic findings were stratified as follows: (i) acute folliculitis with bacteria and/or yeast (n = 9); (ii) lymphocytic perifolliculitis (n = 7); (iii) eosinophilic folliculitis (n = 5); (iv) perifolliculitis with mixed inflammation (n = 11); (v) follicular rupture with predominant granulomatous inflammation (n = 1). Demodex organisms were found in 10 specimens scattered among these categories. CONCLUSIONS: The histopathology of folliculitis in HIV-infected patients is protean. No single factor could be identified as the cause, making targeted antibacterial or antifungal therapy unlikely to be successful across a wide range of patients.

Female↗
PubMed2002

Does ultrastructural morphology of human detrusor smooth muscle cells characterize acute urinary retention?

PURPOSE: Acute urinary retention is relatively rare in otherwise healthy men. The condition may be attributable to a combination of obstruction and detrusor hypocontractility. We determined whether acute or chronic urinary retention is accompanied by characteristic ultrastructural features in bladder detrusor smooth muscle cells and whether any of these ultrastructural features may be useful for classifying these conditions. MATERIALS AND METHODS: Bladder biopsies of 15 men, including 13 in acute and 2 in chronic urinary retention, and 6 controls were examined by transmission electron microscopy. They were semiquantitatively and morphometrically analyzed for degenerative changes, cellular hypertrophy, variations in intercellular distances, abnormal cell junctions and configurations, and intracellular changes. RESULTS: No significant ultrastructural features were noted in the detrusor muscle of patients in acute urinary retention compared with controls. CONCLUSIONS: We cannot confirm the reports of others that characteristic ultrastructural features in smooth muscle cells accompany bladder outlet obstruction and detrusor hypocontractility.

Acute Disease↗
PubMed2000

Stimulation of Schwann cell proliferation and axonal regeneration by FK 506.

PURPOSE: Nerve allografts are highly antigenic and, thus, require the continuous use of immunosuppressive drugs. FK 506 was found to pre-vent rejection successfully. However, clinically neurotoxic complications have been noted in the central and peripheral nervous system although an increased rate of axonal regeneration has also been shown after nerve crush experiments. To investigate whether a possible regeneration pro-moting potency of FK 506 is determined via an influence on Schwann cells, Schwann cells were cultured from the sciatic nerve of the rat. METHODS: The effect of 100 micro M FK 506 administered daily on these cultures was assessed microscopically over a period of seven days and compared to an untreated control group of cultures. Additionally, the changes in intracellular calcium were recorded using a laser scanning microscope. In vivo regeneration of autologous rat sciatic nerve grafts was assessed clinically, histologically and morphometrically after two and six weeks. The animals received a daily administration of 0.6 mg FK 506/kg body weight, the control received saline. RESULTS: In vitro FK 506 increased the Schwann cell number in culture significantly compared to non treated cultures, while the fibrocyte population was decreased. FK 506 caused a transient increase of intracellular calcium levels in cultured cells. In vivo, a significantly higher axon count was observed in the FK 506 treated grafts after two weeks regeneration compared with controls. Good regeneration was noted in all grafts after six weeks regeneration. CONCLUSIONS: The increased axon counts and decreased myelin debris in the FK 506 grafts after two weeks indicate an accelerated Wallerian degeneration and increased axon sprouting into the graft initially. The inhibition of calcineurin activity is not the mediator of the neurotrophic effect. FK 506 promotes axonal regeneration through binding to FKBP-12. The increase of intracellular calcium may induce Schwann cell pro-liferation via calmodulin. The therapeutic relevance for autologous nerve grafting, however, has to be defined in further studies.

Journal Article↗
PubMedDate not supplied

Incorporation of chemoselective functionalities into peptoids via solid-phase submonomer synthesis.

A simple route to the introduction of a number of chemoselective functional groups into peptoids (oligo(N-substituted glycines)) by an extension of the standard solid-phase submonomer method is reported. The following groups were introduced: aminooxyacetamide, N-(carbamoylmethyl)acetohydrazide, mercaptoacetamide, 2-pyridinesulfenylmercaptoacetamide, and aldehyde-terminated peptoids. The method uses commercially available reagents, is fully compatible with standard peptoid submonomer synthesis conditions, is easily automated, and generates the desired functionalized peptoid in high yield and purity. Peptoids with suitable pairs of chemoselective ligation groups were joined in high yield.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Subcellular localization of intercellular adhesion molecule-1 in colonic mucosa in ulcerative colitis.

Intercellular adhesion molecule-1 (ICAM-1) mediates the firm adhesion of leukocytes to endothelial cells. In ulcerative colitis (UC), ICAM-1 is suggested also to be involved in the further migration of leukocytes toward the epithelial lining, and in colonic tissue it has been reported to be expressed by cell types other than endothelial cells. This study aimed at determining the ultrastructural localization of ICAM-1 on cells belonging to the colonic mucosa from patients with UC. Colonic biopsies from 3 UC patients and 3 control subjects were examined ultrastructurally by immunogold labeling of ICAM-1. ICAM-1 was expressed on the luminal cell membranes of endothelial cells in both controls and inflamed and noninflamed UC colon, although the density was significantly increased in UC (p < .0001). Labeling was observed on the basal endothelial cell membranes and on macrophages and plasma cells in inflamed UC colon only. Epithelial cells did not express ICAM-1. ICAM-1 appears to be constitutively upregulated on the luminal endothelial membrane in UC, and the expression on basal endothelial membranes in active UC only suggests that ICAM-1 is more extensively involved in the leukocyte migration than previously acknowledged.

Biopsy↗
PubMedDate not supplied

New evaluation of plasma DNA microsatellite analysis in patients with TCC of the urinary bladder.

BACKGROUND: To determine the diagnostic value of plasma DNA microsatellite analysis in patients with transitional cell carcinoma (TCC) of the urinary bladder, by redefining plasma LOH from the equivalent analysis in controls. The method was further tested for MSI (microsatellite instability) and compared with tissue DNA analysis. MATERIALS AND METHODS: Sixteen microsatellites were amplified in leukocyte, plasma and tissue DNA from 40 patients and 28 controls, and analysed in a laser-based, capillary electrophoresis system. Plasma LOH was determined from the controls' cut-off values. RESULTS: The difference between plasma LOH frequency in patients (25% (10/40)) and controls (14% (4/28)) was not significant. Nevertheless, it occurred significantly more often in low rather than high-grade tumors (p=0.03) and controls (p=0.04). Plasma MSI was dependent upon the number of PCR cycles. Tissue LOH was present in 78% (31/40) of the patients and in none of the controls. Tissue MSI was uncommon. CONCLUSION: The results of plasma DNA microsatellite analysis in TCC need cautious interpretation.

Carcinoma, Transitional Cell↗
PubMedDate not supplied

Under-representation of bladder transitional cell tumour 9q, 11p and 14q LOH in urine and impact on molecular diagnosis.

BACKGROUND: To investigate whether the recently reported evidence of differences in the overall loss of heterozygosity (LOH) frequency between urine and tumour tissue in patients with transitional cell tumours (TCT) of the urinary bladder involved specific chromosomal sites, and their impact in diagnosis. MATERIALS AND METHODS: Blood, tissue and urine specimens were obtained from 55 patients and 25 controls. Sixteen microsatellites were PCR-amplified and blindly analyzed for LOH through a laser-based capillary electrophoresis system. RESULTS: Significant frequence differences between tumour tissue and urine sediment LOH were found in 9q and 11p in non-invasive disease and 14q in invasive disease. There was no significant difference for all the other chromosomal arms analyzed. CONCLUSION: The contribution in the urine sediment of cells belonging to tumours of the same histological classification differs according to the specific genetic alterations these cells carry. Furthermore, the location regarding these differences could indicate regions involved in tumour exfoliation or apoptosis.

Aged↗