Biomedical subjects
J Peltonen
Publications and source records attributed to J Peltonen.
The effects of sialic acid on the gene expression of fibrillar collagens: different changes in normal and fibrotic scar derived fibroblasts.
OBJECTIVE: To investigate the effect of free sialic acid on collagen gene expression in fibroblasts. DESIGN: Cell culture study. SETTING: University hospital, Finland. CELL LINES: Human granulation tissue fibroblasts, human hypertrophic scar fibroblasts and human keloid fibroblasts. INTERVENTIONS: Treatment of cell cultures with 3 microM, 30 microM and 300 microM N-acetyl-neuraminic acid. MAIN OUTCOME MEASURES: The measurement of steady state level of mRNA for type I and type III collagen. RESULTS: Fibroblast lines react dissimilarly under the influence of sialic acid. Granulation tissue fibroblasts showed decrease in the gene expression of type I and III collagen, while keloid fibroblasts contrastingly showed an increase. Hypertrophic scar derived fibroblasts showed no change. CONCLUSIONS: Sialic acids may decrease collagen gene expression in granulation tissue and that disturbed wound healing in diabetics and smokers may in part be due to direct effect of sialic acids on fibroblasts. Sialic acids may in part induce keloid formation.
Effects of glucose on collagen mRNA levels and collagen secretion in EAhy 926 endothelial cell line.
Diabetes mellitus (DM) is a complex metabolic disease associated with increased accumulation of extracellular matrix by endothelial cells and contributing to vascular complications of long-standing diabetes. On the other hand, DM is also associated with decreased accumulation of extracellular matrix in granulation tissue, which is suggested to be a consequence of impaired angiogenesis. The role of hyperglycemia in these situations is not fully understood. We examined the effects of high glucose concentrations on the gene expression and secretion of various collagens in cultured EAhy 926 endothelial cells. EAhy 926 endothelial cells expressed alpha1(I) collagen mRNA at a low level and small amount of the corresponding peptide was secreted from the cells; mRNA was not affected but peptide secretion was increased by elevated glucose concentration. mRNAs for type III and VI collagens were not detected in the endothelial cells. Furthermore, high glucose concentration in long term had no morphological effects on cultured endothelial cells but increased the expression of type IV collagen, which could rather be beneficial for angiogenesis in a healing wound. Our results suggest that high glucose concentration per se may contribute to increased accumulation of extracellular matrix in blood vessels but probably is not responsible for decreased angiogenesis and granulation tissue formation in diabetic patients.
Occult neurofibroma and increased S100 protein in the skin of patients with neurofibromatosis type 1: new insight to the etiopathomechanism of neurofibromas.
BACKGROUND: Neurofibromas represent proliferation of the connective tissue cells of peripheral nerves and deposition of collagenous extracellular matrix. There is evidence that the appearance and growth of neurofibromas may be associated with prior or ongoing mechanical trauma in patients with neurofibromatosis type 1 (NF1). OBJECTIVE: To study the histologic characteristics of apparently healthy skin of patients with NF1. DESIGN: The histologic features of healthy-looking skin of patients with NF1 were analyzed. SETTING: University hospital. PATIENTS: Ten patients who fulfilled the criteria for NF1. INTERVENTIONS: Punch biopsy specimens of healthy-looking skin of the forearm from 9 volunteer patients and of the upper eyelid during cosmetic operation from 1 volunteer patient were obtained. MAIN OUTCOME MEASURES: The main outcomes were not predicted, and the hypothesis was formulated during data collection. RESULTS: Apparently unaffected skin of 5 patients with NF1 was studied by routine histologic testing with respect to expression of S100 protein. Unexpectedly, analysis of the samples revealed the presence of a small neurofibroma tumor in one of the samples. The tumor was located in deep dermis around a hair follicle. In addition, neurofibromatous tissue not large enough to be called a tumor was found on the same anatomical location in another patient. In further studies, 10 punch biopsy specimens of apparently healthy skin from patients with NF1 were similarly sectioned and analyzed. No tumors were found in these additional samples. In 4 patients, however, abundant S100 protein-positive cells were located within collagenous extracellular matrix surrounding hair follicles. CONCLUSIONS: The skin of patients with NF1 might be more widely affected than previously thought and occult neurofibromas are not rare.
Oscillation and rapid changes of NF1 mRNA steady-state levels in cultured human keratinocytes.
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New function for NF1 tumor suppressor.
The expression and subcellular localization of neurofibromatosis type 1 tumor suppressor was studied in keratinocytes induced to differentiate by increased Ca2+ concentration of the culture medium. Differentiating keratinocytes became intensely immunoreactive for neurofibromatosis type 1 protein, which was apparently associated with cellular fibrils. Double immunolabeling with antibodies to cytokeratin 14 and neurofibromatosis type 1 protein suggested an association of intermediate type cytoskeleton and neurofibromatosis type 1 protein. The presence of neurofibromatosis type 1 protein in cell preparations treated with cytoskeletal buffer indicated a high affinity interaction between intermediate filaments and neurofibromatosis type 1 protein. Further studies utilizing double immunolabelings revealed that the intense neurofibromatosis type 1 tumor suppressor signal on intermediate filaments was temporally limited to the period in keratinocyte differentiation in which the formation of desmosomes takes place. Keratinocytes were also cultured from nine patients with type 1 neurofibromatosis and were studied with respect to cell morphology, and association of neurofibromatosis type 1 protein with intermediate cytoskeleton. The results showed that keratinocytes cultured from patients with neurofibromatosis type 1 displayed a highly variable cell size and morphology compared to controls. The latter findings represent predicted alterations in a situation where cytoskeletal organization is disturbed. Furthermore, differentiating neurofibromatosis type 1 keratinocytes were characterized by a reduced number of cytokeratin bundles that were decorated neurofibromatosis type 1 protein. The results of this study suggest that neurofibromatosis type 1 tumor suppressor exerts its effects in part by controlling organization of cytoskeleton during the formation of cellular contacts.
Psoriasis and altered calcium metabolism: downregulated capacitative calcium influx and defective calcium-mediated cell signaling in cultured psoriatic keratinocytes.
Intracellular calcium plays an important part in the regulation of proliferation and differentiation of keratinocytes. Detached from their in vivo environment, cultured psoriatic keratinocytes were investigated by monitoring free intracellular calcium concentration, which was measured using fura-2/AM as a calcium-sensitive probe. The mean increase in intracellular calcium of psoriatic keratinocytes was significantly reduced compared with control keratinocytes when intracellular calcium stores were mobilized from endoplasmic reticulum with thapsigargin. This finding suggests defective capacitative calcium influx of psoriatic cells. Intracellular calcium stores were similar in psoriatic and control keratinocytes, when extracellular calcium was chelated with ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N',-tetraacetic acid and intracellular calcium was depleted with thapsigargin. Mechanical wounding of keratinocyte monolayer resulted in a significantly reduced rise in intracellular calcium of psoriatic cells in low (< 0.1 mM) and high (1.8 mM) extracellular calcium suggesting defective intercellular coupling of psoriatic keratinocytes. Blocking of gap-junctions with heptanol in wounded keratinocytes did not affect the intracellular calcium response in psoriatic keratinocytes in contrast to healthy keratinocytes. Adding adenosine triphosphate to culture medium resulted in a more pronounced intracellular calcium increase than thapsigargin in psoriatic keratinocytes, suggesting that inositol triphosphate-mediated, P2-purinergic signaling was enhanced in these cells. Moreover, psoriatic keratinocytes maintained their defective responses up to at least fifth passage suggesting that psoriatic keratinocytes have an inborn error in calcium metabolism, rather than a localized defect in response to altered extracellular calcium gradient observed in vivo.
Botulinum toxin injection as an adjunct when planning hand surgery in children with spastic hemiplegia.
The usefulness of botulinum toxin A treatment when planning hand surgery in eight children with spastic hemiplegia was evaluated. The hand function of the children was assessed before and after treatment using a test battery consisting of quantitative and qualitative functional assessment. The results of preoperative botulinum treatment supported surgical intervention in four children and serial botulinum treatment in three children. In one child, the preoperative botulinum treatment provided no additional information. We conclude that preoperative botulinum A treatment in most children with spastic hemiplegia, for whom hand surgery is being considered, identifies the patients who would not benefit from the planned surgery or for whom the functional benefit would probably not outweigh the burden of surgical procedure and postoperative rehabilitation.
Cervical kyphosis in diastrophic dysplasia.
STUDY DESIGN: An evaluation of cervical kyphosis in diastrophic dysplasia from newborn to adult life. OBJECTIVES: To discover the prevalence and natural history of cervical kyphosis in diastrophic dysplasia. SUMMARY OF BACKGROUND DATA: Typical findings in this rare skeletal dysplasia are sport-limbed short stature, multiple joint contractures, early degeneration of joints, and spinal deformities such as cervical kyphosis, scoliosis, and exaggerated lumbar lordosis. In diastrophic dysplasia, spontaneous resolution of cervical kyphosis has been reported, but so have severe forms causing medullar compression leading to quadriplegia and death. The prevalence and clinical outcome of the kyphosis are not known. METHODS: The radiographic natural history of the cervical spine was studied in 120 patients. They varied in age from newborns to 63-year-olds. The average follow-up time in 26 living patients with cervical kyphosis was 10.0 years. RESULTS: Midcervical kyphosis was noted in 29 patients (24%) in their first radiograph. In 25 patients, the first radiographs were taken before the age of 18 months, and 24 of these patients (96%) had cervical kyphosis. The most severe case was that of a 32-year-old patient with a 165 degrees kyphosis. In the 24 patients, the kyphosis resolved spontaneously at an average age of 7.1 years. Three patients with a severe kyphosis died; one patient is alive. One patient, a 4-year-old child has mild resolving deformity. CONCLUSIONS: Cervical kyphosis in diastrophic dysplasia usually is shown at the time of birth. It resolves spontaneously during growth and seldom needs treatment. Careful follow-up study and treatment, if necessary, are important tools for avoiding the neurologic problems and fatal outcome.
Highly efficient immobilisation of antibody fragments to functionalised lipid monolayers.
The covalent attachment of Fab' fragments of polyclonal anti-human IgG to a lipid with a terminal linker group was examined by means of quartz crystal microbalance and surface plasmon resonance measurements. The linker lipid was embedded in binary or ternary monolayers of dipalmitoylphosphatidylcholine (DPPC) and cholesterol. Atomic force microscopy images of the films deposited on silanised SiO(2) substrates showed that Fab' fragments take a standing position, thus giving site-directed immobilisation. Human IgG forms a network on interaction with the antibodies. Non-specific binding of bovine serum albumin was found to be very low when DPPC was used as the host matrix. At an optimal Fab' fragment concentration a binding capacity above 60% was obtained. However, if the surface concentration of the immobilised antibodies was too high, the binding capacity decreased due to steric hindrance. The results demonstrate that the covalent coupling of Fab' fragments to N-(epsilon-maleimidocaproyl)-dipalmitoylphosphatidylethanolamine (DPPE-EMC) embedded in a host monolayer matrix of DPPC is a promising approach to achieve a site-directed immobilisation of antibodies with high antigen-binding efficiency.
Increase of collagen synthesis and deposition in the arachnoid and the dura following subarachnoid hemorrhage in the rat.
Arachnoidal fibrosis following subarachnoid hemorrhage (SAH) has been suggested to play a pathogenic role in the development of late post-hemorrhagic hydrocephalus in humans. The purpose of this study was to investigate the rate of collagen synthesis in the arachnoid and the dura in the rat under normal conditions and to study the time schedule and the localization of the increased collagen synthesis following an experimental SAH. We found that the activity of prolyl 4-hydroxylase, a key enzyme in collagen synthesis, was 3-fold higher in the dura than that in the arachnoid and was similar to the activity in the skin. We then induced SAH in rats by injecting autologous arterial blood into cisterna magna. After SAH, we observed an increase in prolyl 4-hydroxylase activity of the arachnoid and the dura at 1 week. At this time point the enzyme activity in both tissues was 1.7-1.8-fold compared to that in the controls and after this time point the activities declined but remained slightly elevated at least till week 4. The rate of collagen synthesis was measured in vitro by labeling the tissues with [(3)H]proline. The rate increased to be 1.7-fold at 1 to 2 weeks after the SAH in both of the tissues. Immunohistochemically we observed a deposition of type I collagen in the meninges at 3 weeks after the SAH. SAH is followed by a transient increase in the rate of collagen synthesis in the arachnoid and, surprisingly, also the dura. Increased synthesis also resulted in an accumulation of type I collagen in the meningeal tissue, suggesting that the meninges are a potential site for fibrosis. The time schedule of these biochemical and histological events suggest that meningeal fibrosis may be involved in the pathogenesis of late post-hemorrhagic hydrocephalus.
Urinary bladder transitional cell carcinogenesis is associated with down-regulation of NF1 tumor suppressor gene in vivo and in vitro.
The NF1 gene product (neurofibromin) is known to act as a tumor suppressor protein by inactivating ras. The best documented factors involved in urinary bladder transitional cell carcinoma (TCC) are ras proto-oncogene activation and p53 suppressor gene mutations. This is the first study reporting alterations in NF1 gene expression in TCC. We examined NF1 gene expression in a total of 29 surgical urinary bladder TCC specimens representing grades 1 to 3 and in three cell lines, RT4, 5637, and T24 (representing grades 1 to 3, respectively). Decreased NF1 gene expression was observed in 23 of 29 (83%) TCC specimens as estimated by immunohistochemistry, the decrease being more pronounced in high-grade tumors. NF1 mRNA levels were markedly lower in TCC tissue compared with adjacent non-neoplastic urothelium, as studied by in situ hybridization for grade 3 TCC. Immunohistochemistry and Western blotting demonstrated that TCC cell lines expressed NF1 protein at different levels, expression being almost undetectable in T24 (grade 3) cells. Northern blotting for cell lines demonstrated reduced NF1 mRNA levels in grade 3 TCC cells. Reverse transcription polymerase chain reaction for cell lines and selected grade 2 and grade 3 tissue samples demonstrated NF1 type II mRNA isoform predominance in all samples studied. Our results show that both NF1 mRNA and protein levels are decreased in high-grade TCC, suggesting that alterations of NF1 gene expression may be involved in bladder TCC carcinogenesis.
UV-induced reaction kinetics of dilinoleoylphosphatidylethanolamine monolayers.
The UV-induced reactivity of dilinoleoylphosphatidylethanolamine (DLiPE) Langmuir and Langmuir-Blodgett films has been studied by in situ measurements of the changes in the mean molecular area, UV-vis and Fourier transform infrared spectroscopy, and atomic force microscopy (AFM). Optimum orientation and packing density of the DLiPE molecules in the monolayer were achieved by adding uranyl acetate to the subphase. A first-order reaction kinetic model was successfully fitted to the experimental reaction kinetics data obtained at a surface pressure of 30 mN/m. Topographical studies of LB films by AFM were performed on bilayer structures as a function of subphase composition and UV irradiation time. The orientational effect of the uranyl ions on the monolayer molecules was observed as an enhanced homogeneity of the freshly prepared monomeric LB films. However, the long-term stability of these films proved to be bad; clear reorganization and loss of a true monolayer structure were evidenced by the AFM images. This instability was inhibited for the UV-irradiated films, indicating that the UV irradiation gave rise to a cross-linked structure.
A novel component of epidermal cell-matrix and cell-cell contacts: transmembrane protein type XIII collagen.
Type XIII collagen is a short chain collagen which has recently been shown to be a transmembrane protein. The purpose of this study was to elucidate the presence and localization of type XIII collagen in normal human skin and cultured keratinocytes. Expression of type XIII collagen was demonstrated in normal human skin and epidermis at the RNA level using reverse transcription followed by polymerase chain reaction and at the protein level using western blotting and indirect immunofluorescence labeling. Immunolabeling of epidermis revealed type XIII collagen both in the cell-cell contact sites and in the dermal-epidermal junction. In cultured keratinocytes type XIII collagen epitopes were detected in focal contacts and in intercellular contacts. The results of this study show very little colocalization of type XIII collagen and desmosomal components at the light microscopic level. Thus, these results suggest that type XIII collagen is unlikely to be a component of desmosomes. Instead, the punctate labeling pattern of type XIII collagen at the cell-cell contact sites and high degree of colocalization with E-cadherin suggests that type XIII collagen is very likely to be closely associated with adherens type junctions, and may, in fact, be a component of these junctions.
Effects of hexose sugars: glucose, fructose, galactose and mannose on wound healing in the rat.
The effects of four hexose sugars (D-glucose, D-fructose, D-galactose, D-mannose) on the developing granulation tissue in rats were examined. Cylindrical hollow sponge implants were used as an inductive matrix for the growth of granulation tissue. In the test group, the implants were injected with 0.1 ml of solution containing the different hexoses in 0.01, 0.1 and 1 M concentrations daily for 7 days while the implants of the control groups were injected with 0.1 ml of phosphate-buffered saline solution only. Analyses of granulation tissue and wound fluid in the sponge implants were carried out 7 days after implantation. The results demonstrated that galactose caused a significant increase in the accumulation of granulation tissue as estimated by histological analyses, but no significant differences were observed in various chemical analyses. In striking contrast, statistically significant decreases were observed in the number of leukocytes in wound fluid, in the amount of DNA, RNA, collagen hydroxyproline, nitrogen, hexosamines and uronic acids in sponges treated with 0.1 or 1 M mannose, reflecting decreased granulation tissue formation. This effect was also observed in histological analyses of the specimens. There were no major changes in sponges treated with glucose or fructose. In summary, the findings of the present study demonstrate that galactose may enhance wound healing and mannose treatment inhibits the inflammatory reaction in wound healing and decreases granulation tissue formation in an experimental wound model.
The knee joint in diastrophic dysplasia. A clinical and radiological study.
We examined clinically and radiologically the knees of 46 patients (27 females and 19 males) with diastrophic dysplasia. The age of the patients varied from newborn to 38 years. A total of 18 patients was followed during their growth until adolescence. The knees of two legally aborted fetuses appeared on examination to be macroscopically normal and congruous. Excessive valgus deformity of the tibiofemoral weight-bearing angle with a mean of 14 degrees was noted in infancy. Most of the patients had marked instability of the knees. The range of movement of the knee began to decrease before the age of five years. There were signs of early degeneration and deformation of the bony epiphyses before the age of six years. The patellofemoral joint was abnormal from an early age. A marked patella infera, often associated with a lateral position of the patella with bony fragmentation, was noted. The knee in diastrophic dysplasia is basically unstable, showing early deformation of the subchondral bone and degeneration of the joint.
Health-related quality of life in patients with diastrophic dysplasia.
Diastrophic dysplasia (DD), a congenital skeletal dysplasia, is characterized by short, disproportionate stature, multiple severe spinal and joint deformities, and normal mental status. The health-related quality of life (HRQOL) of patients with DD was measured by a standardized fifteen-dimensional (15D) method, that includes a questionnaire and a valuation task. Eighteen patients (5 males and 13 females) with a mean age of 23 years (range 17-31 years), representing half of the Finnish patients with DD in this age group, completed the questionnaire and the valuation task. The data obtained were compared with those of 273 age- and sex-matched controls. A 15D profile was drawn, and the average importance weight of each dimension and the average within-dimension level values were calculated for both groups. The average 15D score, describing the overall HRQOL, was derived for both groups using the evaluations of each group. The health profiles of the groups differed significantly in several dimensions. When the health levels within the dimensions were concerned, the controls rated all values deviating from "normal" lower than did the patients. The average 15D scores of the patients with DD were significantly lower than those of the controls. The 15D scores were higher in both groups when the evaluations of the patients with DD were used. The study showed that, although the overall HRQOL of the patients with DD was inferior to that of the controls, the patients showed greater adaptability to deviations in health status than did the controls.