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Biomedical subjects

J Uitto

Publications and source records attributed to J Uitto.

At least 451 records · Page 25Linked to original sources
PubMed1985

Mitral valve prolapse in sickle cell disease: manifestation of a generalized connective tissue disorder.

Previous studies have shown an association of sickle cell disease with generalized connective tissue disorders such as pseudoxanthoma elasticum. We recently documented an unexpectedly high prevalence of mitral valve prolapse, a connective tissue disorder, in sickle cell disease. To investigate this association, skin biopsies were analyzed from 32 sickle cell disease patients, 11 of whom had mitral prolapse. Total and type III collagen, collagen solubility, and uronic acid were not different between the patients with or without mitral prolapse (p greater than 0.05). Computerized morphometric quantitation of the volume fraction of elastic fibers was greater in sickle cell disease patients than in 10 normals (3.1 +/- 0.1 mean +/- SEM vs 2.0 +/- 0.3%; p less than 0.01) but less than in three patients with pseudoxanthoma elasticum (9.7 +/- 0.6%; p less than 0.001). Desmosine radioimmunoassay (an index of elastic fibers) was greater in sickle cell disease patients with mitral prolapse than those without (239.3 +/- 9.3 vs 171.7 +/- 25.4 ng/mg wet weight; p less than 0.02). Histopathologic grading showed a similar trend (p = 0.07). The combined probabilities of these three independent tests of elastic fiber quantity showed an increased elastic fiber concentration in mitral prolapse patients compared to those without mitral prolapse (p less than 0.02). Thus, there is no evidence for a specific collagen defect; rather, sickle cell disease appears to be associated with a spectrum of elastic tissue disorders, a feature that could predispose to mitral valve prolapse.

Adolescent↗
PubMed1985

Computer analysis of laser dosimetry data: a method of accurate energy density delivery.

In the past, utilization of the laser in medicine has been limited by the lack of accurate quantification of the energies delivered to the tissue. Data obtained in the course of this investigation have demonstrated the relationships which exist between the energy delivered to the tissue and the optical system composed of the fiber and focusing lens. A continuous-wave multimode Nd:YAG laser (1,064 nm) was used in these experiments. Utilizing the beam scan technique previously described, we recorded over 100 beam profiles at various distances from the handpiece (fiber optic and lens). Computer analysis of our data established the mathematical correlation between the surface area of the irradiated spot and the distance of the handpiece to the target, thus allowing us to predict the surface area of the irradiated spot to any desired distance. By duplicating our methods with his particular optical system, the clinician or any laser user has the capacity to determine the energy delivered to the tissue (J/cm2) by knowing the power of the laser (watts), the time of exposure (seconds), and the distance of the handpiece to the treatment site (centimeters).

Computers↗
PubMed1985

Altered steady-state ratio of type I/III procollagen mRNAs correlates with selectively increased type I procollagen biosynthesis in cultured keloid fibroblasts.

Regulation of collagen gene expression was studied in fibroblast cultures established from patients with keloids, fibrotic lesions of the skin. In selected keloid fibroblast cultures, an overproduction of type I procollagen was observed. This increase was accompanied by a parallel increase in type I procollagen-specific mRNA levels, as detected by dot-blot and RNA transfer hybridizations, without concomitant change in type I procollagen gene copy number. At the same time, type III procollagen mRNA levels were unaltered, resulting in markedly elevated type I/III procollagen mRNA ratios. Thus, keloid fibroblasts offer a unique model to study the independent regulation of the gene expression of two genetically distinct procollagens, type I and type III.

Cells, Cultured↗
PubMed1985

Biochemical composition of the connective tissue in keloids and analysis of collagen metabolism in keloid fibroblast cultures.

Keloids are histologically characterized by an abundance of the extracellular matrix of connective tissue. In the present study, we examined the connective tissue composition of keloids, and analyzed the details of collagen metabolism utilizing fibroblast cultures established from keloid tissue. Quantitative connective tissue analyses indicated that collagen was the predominant extracellular matrix component in keloids. The ratio of genetically distinct collagens type I/III was significantly increased, as compared to normal human skin. Collagen biosynthesis was measured in fibroblast cultures by the formation of radioactive hydroxyproline: 5 of 9 keloid cell cultures studied demonstrated increased procollagen production in comparison to age-, sex-, and passage-matched control skin fibroblast lines, while the remaining 4 cell lines were within the control range. Keloid fibroblast cultures which were high collagen producers also demonstrated elevated prolyl hydroxylase activity. The mechanisms of increased procollagen production in fibroblast cultures were first examined by assaying the abundance of type I procollagen-specific mRNA utilizing dot blot hybridizations with a pro alpha 2(I)-chain-specific cDNA. The type I procollagen mRNA levels were significantly increased in 4 keloid fibroblast lines, and a good correlation between the mRNA levels and the rate of procollagen production in the same cultures was noted. These observations suggest regulation of the collagen gene expression on the transcriptional level. The catabolic pathway of collagen metabolism in fibroblast cultures was examined by determining the degradation of newly synthesized procollagen polypeptides through assay of radioactive hydroxyproline in small-molecular-weight peptide fragments. In 3 keloid cell cultures, the degradation of newly synthesized collagen polypeptides was below the range of normal controls. These findings suggest that a reduced degradation of newly synthesized polypeptides might contribute to the accumulation of procollagen in some keloid fibroblast cultures. The results of this study suggest two possible mechanisms for deposition of collagen in keloid lesions in vivo: first, the growth of the lesions may result from a localized loss of control of the extracellular matrix production by fibroblasts; secondly, reduced degradation of the newly synthesized procollagen polypeptides may contribute to collagen deposition in some keloids.

Adult↗
PubMed1985

Demonstration of cellular retinoic acid binding protein in cultured human skin fibroblasts.

Previous studies have indicated that retinoids, such as all-trans-retinoic acid and 13-cis-retinoic acid, can modulate connective tissue metabolism in human skin fibroblast cultures. Such effects could be mediated through binding of these retinoids to specific cellular binding proteins. In the present study we have demonstrated cellular retinoic acid binding protein using both whole cell and cytosol binding assays with [3H]all-trans-retinoic acid or [3H]13-cis-retinoic acid as the ligand. Specific binding of [3H]all-trans-retinoic acid could be demonstrated by both techniques and the binding could be displaced by unlabelled all-trans-retinoic acid and 13-cis-retinoic acid, but not by retinol or RO-10-9359 (etretinate) in a 100-fold excess. Gel filtration chromatography of the cytosol proteins after incubation with [3H]all-trans-retinoic acid demonstrated that the specific binding protein had an apparent molecular weight of approximately 15 000 daltons. Thus, the cellular retinoic acid binding protein demonstrated in human skin fibroblasts may mediate the effects of the retinoids on connective tissue metabolism in these cells.

Binding, Competitive↗
PubMed1985

Demonstration of elastin gene expression in human skin fibroblast cultures and reduced tropoelastin production by cells from a patient with atrophoderma.

Atrophoderma is a rare dermal disorder characterized by a patchy distribution of areas apparently devoid of elastic fibers. Skin fibroblast cultures were established from the normal and affected dermis of a patient with this disorder. Human tropoelastin was identified in culture medium by use of electroblotting and anti-elastin antisera. An enzyme-linked immunosorbent assay was used to establish that significantly less elastin accumulated in the media of cultured cells from lesional fibroblasts over a 3-d period. Since elastin biosynthesis in most tissues is under pretranslational control, molecular hybridization to a nick-translated genomic elastin probe was performed; however, elastin messenger RNA levels were equivalent in both cell strains. Both strains produced less elastin than did normal skin fibroblasts. Extracellular proteolysis of elastin was evaluated as a possible mechanism. Elastase activity was increased and porcine tropoelastin was degraded four times faster, on a per-cell basis, in lesional fibroblast cultures than in cells derived from an unaffected site. The two cell strains exhibited no significant differences in collagen production or collagenase activity. These results are the first demonstration of elastin production by cultured human skin fibroblasts, and they suggest that the primary defect in atrophoderma may be a result of enhanced degradation of newly synthesized elastin precursors.

Adolescent↗
PubMed1985

Modulation of procollagen gene expression by retinoids. Inhibition of collagen production by retinoic acid accompanied by reduced type I procollagen messenger ribonucleic acid levels in human skin fibroblast cultures.

Recent clinical observations have suggested that retinoids, which are in frequent use in dermatology, can affect the connective tissue metabolism in skin and other tissues. In this study, we examined the effects of several retinoids on the metabolism of collagen by human skin fibroblasts in culture. Incubation of cultured fibroblasts with all-trans-retinoic acid or 13-cis-retinoic acid, in 10(-5) M or higher concentrations, markedly reduced the procollagen production, as measured by synthesis of radioactive hydroxyproline. The effect was selective in that little, if any, inhibition was noted in the incorporation of [3H]leucine into the noncollagenous proteins, when the cells were incubated with the retinoids in 10(-5) M concentration. Similar reduction in procollagen production was noted with retinol and retinal, whereas an aromatic analogue of retinoic acid ethyl ester (RO-10-9359) resulted in a slight increase in procollagen production in these cultures. The reduction in procollagen production by all-trans-retinoic acid was accompanied by a similar reduction in pro alpha 2(I) of type I procollagen specific messenger RNA (mRNA), as detected by dot blot and Northern blot hybridizations. Hybridizations with human fibronectin and beta-actin specific DNA probes indicated that the levels of the corresponding mRNAs were not affected by the retinoids, further suggesting selectivity in the inhibition of procollagen gene expression. Further control experiments indicated that all-trans-retinoic acid, under the culture conditions employed, did not affect the posttranslational hydroxylation of prolyl residues, the mannosylation of newly synthesized procollagen, the specific radioactivity of the intracellular prolyltransfer RNA pool, or DNA replication. All-trans-retinoic acid also elicited a reduction in trypsin-activatable collagenase, but not in the activity of prolyl hydroxylase or an elastaselike neutral protease in the fibroblast cultures. Incubation of three fibroblast lines established from human keloids with all-trans-retinoic acid or 13-cis-retinoic acid also resulted in a marked reduction in procollagen production. The results, therefore, suggest that further development of retinoids might provide a novel means of modulating collagen gene expression in patients with various diseases affecting the connective tissues.

Cells, Cultured↗
PubMed1985

Phenytoin modulates connective tissue metabolism and cell proliferation in human skin fibroblast cultures.

Phenytoin has been proposed for the treatment of certain dermatologic conditions involving connective tissue abnormalities. To understand the biochemical basis of connective tissue changes, we incubated human skin fibroblasts in culture with varying concentrations of phenytoin. The results indicated that fibroblast proliferation, detected by tritiated thymidine incorporation into cells, was slightly stimulated when short incubation periods and low concentrations of phenytoin were employed. However, with longer incubation times and higher phenytoin concentrations, a significant reduction in fibroblast proliferation was observed. Further studies demonstrated that incubation of cells with phenytoin did not affect the production of procollagen, measured as synthesis of radioactive hydroxyproline in the cultures. However, assay of prolyl hydroxylase, an enzyme participating in the post-translational synthesis of hydroxyproline during collagen biosynthesis, was significantly reduced in the fibroblast cultures. The activity of collagenase, an enzyme participating in degradation of collagen, was markedly decreased in cultures treated with phenytoin. Thus, phenytoin may modulate collagen metabolism primarily by affecting the degradation of collagen. The results support previous suggestions that phenytoin may be useful for treatment of patients with increased levels of collagenase, such as in recessive dystrophic epidermolysis bullosa.

Cell Division↗
PubMed1985

Collagen synthesis and collagenase activity in dermal fibroblasts from patients with diabetes and digital sclerosis.

Collagen production and collagenase activity were measured in dermal fibroblast cultures obtained from eight patients with diabetes with digital sclerosis and three normal controls. Total collagen synthesis in patients with diabetes was reduced in comparison with controls. DNA replication was also reduced in patients with diabetes. No differences in collagenase activity were noted. Our results suggest that, in contrast to systemic sclerosis, increased synthesis does not contribute to the collagen accumulation of diabetic digital sclerosis. Decreased degradation related to nonenzymatic glucosylation of collagen is a more likely mechanism.

Adult↗
PubMed1985

Connective tissue alterations in skin exposed to natural and therapeutic UV-radiation.

Aging of human skin represents a complex situation where several factors contribute to the age-related changes. One of these factors relates to UV-radiation, but the exact mechanistic details are not well established. Several morphologic studies have indicated definite changes in the quantitative aspects of dermal connective tissue components, collagen and elastin. Also, recent biochemical studies have suggested that UV-irradiation can alter the metabolism of these proteins in the skin. This review summarizes the current state of knowledge of the effects of natural and therapeutic UV-radiation on dermal connective tissue, and further delineates additional research needs necessary for disclosure of the exact mechanistic details of the aging processes in human skin.

Animals↗
PubMed1985

Characterization and partial purification of a neutral protease from the serum of a patient with autosomal recessive pulmonary emphysema and cutis laxa.

Serum enzyme activity in 81 patients with various medical and dermatologic problems was determined with succinyl-(L-alanyl)3-p-nitroanilide as substrate. Values exceeding the limit of mean +/- 3 SD in healthy controls were detected in 16 patients. The highest activity, greater than 80 times the mean in the controls, was found in a 20-year-old patient with severe pulmonary emphysema and cutis laxa. The enzyme activity in the patient's serum was enhanced by Ca2+ and was inhibited by metal chelators but not by serine protease inhibitors. The pH optimum of the enzyme was 7.6. The enzyme was partially purified by gel filtration chromatography. Enzyme activity eluted in two major peaks with apparent molecular weights of greater than 10(7) daltons (peak I) and approximately 2.5 X 10(5) daltons (peak II). When compared with the elution patterns in the patient's mother and a healthy control, the elevated enzyme activity in the patient's serum was associated with peak I. The partially purified enzyme in peak I was not complexed with alpha 2-macroglobulin. The peak I enzyme was capable of degrading tropoelastin and a synthetic dinitrophenyl peptide at a glycyl-isoleucyl sequence, but not native or denatured collagen.

Adult↗
PubMed1985

Altered skin elastic fibers in hypothyroid myxedema and pretibial myxedema.

Elastic fibers account for 2% of dermal volume and are responsible for normal skin resiliency. We investigated a disorder of the dermal elastic component as the mechanism for the decreased elasticity of skin in myxedema. Skin biopsy specimens were obtained from patients with thyroid diseases and normal subjects matched for age, sex, and biopsy location. Elastic fiber concentration, determined by computerized morphometric analysis of Verhoeff-van Gieson-stained sections, was significantly lower than normal in hypothyroid and pretibial myxedema. The decreased elastin concentration was not a consequence of the glycosaminoglycan infiltration. Ultrastructural studies of myxedematous skin showed wide variability of elastic fiber diameter and decreased microfibrils. Myxedema (hypothyroid and pretibial) is consistently associated with quantitative and qualitative defects of dermal elastic fibers.

Adult↗
PubMed1985

Retinoid modulation of connective tissue metabolism in keloid fibroblast cultures.

Recent observations have suggested that retinoids might affect the metabolism of the extracellular matrix of connective tissues. In this study, we examined the effects of tretinoin (all-trans-retinoic acid) and isotretinoin (13-cis-retinoic acid) on the production of procollagen in keloid fibroblast cultures that were characterized by enhanced procollagen synthesis in vitro. The activities of three enzymes relevant to connective tissue metabolism, prolyl hydroxylase, collagenase, and an elastaselike neutral protease were also determined. The results demonstrated that collagen production was markedly reduced in cultures treated with either one of the retinoids. The activity of prolyl hydroxylase, a key enzyme in the intracellular biosynthesis of collagen, was not affected, while the production of collagenase was markedly reduced by the retinoids. In contrast, the activity of an elastaselike neutral protease in the cell culture medium was markedly enhanced by both retinoids. The results, therefore, indicate a differential modulation of connective tissue metabolism by retinoids in keloid cell cultures.

Cells, Cultured↗
PubMed1985

Marfan's syndrome: structural, biochemical, and mechanical studies of the aortic media.

An intrinsic defect in the aortic media in six patients with Marfan's syndrome, who died of cardiovascular complications of the disease at an average age of 32 years, has been delineated by correlated morphologic, biochemical, and mechanical studies. The findings in the Marfan aortas have been compared with those in age- and sex-matched controls, who died of unrelated diseases without significant aortic lesions, and in three patients with dissecting aneurysms of non-Marfan origin. The results showed that there was a significant reduction in the tensile strength of the aorta in Marfan's syndrome. This finding was correlated by scanning electron microscopy with structural alterations of the medial elastic fibers, including enlarged interlaminar spaces and loss of interlaminar elastic fibrils. No structural alterations were identified in collagen fibers. Biochemical analyses of the aortic media revealed a substantial reduction in aortic elastin content. Furthermore, the desmosine content of the isolated elastin was reduced by approximately 50%. No changes were detected in the composition or solubility of the medial collagen. In contrast to Marfan aortas, the elastin and collagen contents of the dissecting aneurysms of non-Marfan origin were similar to those of the controls. These findings suggest that the vascular complications in Marfan's syndrome may be based on a genetic abnormality affecting elastin fibrillogenesis.

Adult↗
PubMed1984

The production of collagenase by adherent mononuclear cells cultured from human peripheral blood.

Mononuclear cells were isolated from human peripheral blood by Ficoll-Hypaque centrifugation, and the cells adherent to plastic substrata were cultured in serum-free media supplemented with lactalbumin hydrolysate. These cell cultures, which consisted predominantly of monocyte-macrophages as judged by nonspecific esterase staining, accumulated collagenase in the medium. This collagenase resembled other vertebrate collagenases in that it cleaved native triple-helical type I collagen at a locus 3/4-length away from the amino-terminal end of the molecule. The collagenase activity was inhibited by Na2EDTA, dithiothreitol, and fetal calf serum, while the addition of Ca++ or N-ethylmaleimide enhanced the enzyme activity. The accumulation of collagenase in the culture media was markedly enhanced by the incubation of cells with concanavalin A or phorbol myristic acetate. In the presence of cycloheximide, the levels of collagenase activity were markedly reduced, suggesting that active protein synthesis was required to express the enzyme activity. In additional experiments, monocytes were further purified by counterflow centrifugation-elutriation. The collagenase production was markedly increased in cultures enriched in monocyte-macrophages and devoid of polymorphonuclear leukocytes. The accumulation of collagenase in monocyte cultures incubated for 48 hours in the presence of concanavalin A or phorbol myristic acetate was of the same order of magnitude as in parallel cultures containing the same number of polymorphonuclear leukocytes purified by Ficoll-Hypaque centrifugation and Plasmagel sedimentation.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Adhesion↗
PubMed1984

Nonthermal effects of ND:YAG laser on biological functions of human skin fibroblasts in culture.

Previous studies have indicated that laser can selectively affect the biological functions of cells. In the present study, the role of a thermal component in laser-induced alterations in the biology of human skin fibroblasts was examined. Cells were cultured on 96-well tissue culture plates, subjected to treatment with the Nd:YAG laser (wavelength 1,064 nm), and the temperature of the medium was monitored by a microprobe connected to a telethermometer . For comparison, parallel cultures were heated to the same temperatures by tungsten-halogen lamp. The cell cultures were analyzed for collagen synthesis by incubating the cultures with [3H]proline, and the collagen production was assayed by the synthesis of nondialyzable [3H]hydroxyproline. The rate of DNA replication was also determined by measuring the uptake of [3H]thymidine. A marked decrease of collagen production and thymidine incorporation was noted in the cultures subjected to Nd:YAG laser. No such decreases were noted in cultures heated to the corresponding temperatures by tungsten-halogen lamp. The results thus indicate that the biochemical alteration caused by the Nd:YAG laser in human fibroblast functions cannot be explained on the basis of thermal effects.

Collagen↗
PubMed1984

Laser treatment of keloids: a clinical trial and an in vitro study with Nd:YAG laser.

Biochemical studies utilizing keloid fibroblast cultures revealed that Nd:YAG laser selectively suppressed collagen production by these cells. Based on these in vitro observations, eight patients with keloids were treated with Nd:YAG laser in a nondestructive manner. Results, with a 3-year follow-up, indicated flattening and softening of the lesions. Thus, the results suggest that Nd:YAG laser is an effective treatment modality for keloids, and its mechanism may involve bioinhibition of fibroblast functions.

Adult↗