Seizures in patients with trisomy 21

We report on the incidence of seizures in 113 patients with Down Syndrome (DS), 43 coming from the OASI Institute for Research on Mental Retardation and Brain Aging, Troina, and 70 from the outpatient clinic of the Department of Pediatrics, University of Catania. We obtained the following results: 15 (13.2%) patients had seizures; 6 (5.3%) febrile seizures (FS) and 9 (7.9%) afebrile seizures (aFS). Among the latter group 2 patients had generalized tonic-clonic seizures, 3 partial complex seizures, and 4 infantile spasms. The seizures appeared early in life. Only 2 adult patients had seizures. These results suggest that patients with DS show a higher incidence of FS and of aFS than non-DS individuals. Seizures in DS may be an epiphenomenon of the neurological abnormalities, both anatomical and functional, usually observed in these patients.

Lack of Histocompatibility Leukocyte Antigen-G expression in early embryos is not related to germinal defects or impairment of interleukin-10 production by embryos

The expression of Histocompatibility Leukocyte Antigen (HLA)-G molecules is a mandatory prerequisite for the development of pregnancy but no hypotheses have yet been advanced regarding the lack of HLA-G modulation expression in a percentage of early embryos obtained by in vitro fertilization (IVF). One possible hypothetical model assumes that the absence of regulation of HLA-G or impaired interleukin (IL)-10 secretion could be related to germinal defects. We investigated the presence of soluble HLA-G antigens in supernatants of single embryo cultures from couples admitted to a second fertilization procedure; these couples showed a complete absence of HLA-G modulation in the first cycle's embryo supernatants (0/31). The results obtained in the second IVF cycle showed embryo supernatants positive for HLA-G (14/40), suggesting that the previous lack of antigen modulation is independent of germinal defects. Furthermore, since it has been reported that oocytes and early embryos can secrete IL-10, an anti-inflammatory cytokine produced by type 2 helper T cells that induces upregulation of HLA-G expression in monocytes and trophoblasts, we investigated the levels of IL-10 and soluble HLA-G in 40 embryo culture supernatants from 21 IVF cycles. No associations were observed between the presence of IL-10 and the production and concentrations of soluble HLA-G, or between IL-10 levels and pregnancy outcome. These results indicate that the lack of HLA-G production in early embryos is not related to germinal defects or to impairment in embryo IL-10 secretion but could be ascribed to possible uncorrected fertilization processes.

Defective production of soluble HLA-G molecules by peripheral blood monocytes in patients with asthma

BACKGROUND

HLA-G, a human nonclassic MHC class I molecule, is responsible for complex immunoinhibitory functions. HLA-G is expressed as membrane-bound and is secreted as soluble molecules by the peripheral blood CD14+ monocytes activated by IL-10.

OBJECTIVE

It has been reported that LPS stimulation induces IL-10 production by PBMCs and that IL-10 levels are reduced in patients with severe asthma compared with patients with mild asthma and healthy subjects. The study was designed to investigate whether this impaired IL-10 production can affect the expression and the secretion of soluble HLA-G (sHLA-G)-1/HLA-G5 molecules.

METHODS

We investigated the production of sHLA-G1/HLA-G5 and IL-10 by specific ELISAs in the culture supernatants of LPS-activated PBMCs from 24 healthy subjects and 20 patients with moderate to severe persistent asthma.

RESULTS

LPS stimulation induced the secretion of IL-10 and sHLA-G1/HLA-G5 molecules in all healthy subjects, whereas in patients with asthma, the levels of IL-10 were significantly lower (P < .001) and the number of cultures exhibiting detectable sHLA-G1/HLA-G5 was reduced (7/20; P < .001). The addition of exogenous IL-10 to LPS-stimulated PBMCs from patients with asthma restored normal sHLA-G1/HLA-G5 production.

CONCLUSION

Our data suggest that a specific deficit of IL-10 secretion in patients with asthma could prevent the normal production of sHLA-G1/HLA-G5 molecules. The reduction of immunosuppressive activity mediated by HLA-G could in turn contribute to the persistence of chronic airway inflammation in asthma.

The HLA-G genotype is associated with IL-10 levels in activated PBMCs

Human leukocyte antigen (HLA)-G is an MHC class Ib molecule that is expressed at the feto-maternal interface during pregnancy. However, recent results have also shown that it may have important functions as an immuno-modulatory factor in adult life. Differences in the pattern of alternative splicing and in the stability of HLA-G mRNA transcripts have been associated with HLA-G polymorphisms, especially a 14 bp deletion/insertion polymorphism in the 3' untranslated region of the HLA-G gene. We have investigated the secretion of HLA-G5/soluble HLA-G1 and interleukin-10 (IL-10) in lipopolysaccharide (LPS)-activated peripheral blood mononuclear lymphocytes (PBMCs) in relation to the HLA-G 14 bp genotype. No HLA-G5/sHLA-G1 could be detected in the non-activated control PBMC culture media, and there were no significant differences among the three HLA-G 14 bp genotypes regarding IL-10 concentrations. In LPS-activated PBMC cultures, no significant differences among the three HLA-G 14 bp genotypes regarding HLA-G5/sHLA-G1 concentrations were observed. However, this was in contrast to the IL-10 levels (P=0.0004, Kruskal-Wallis test). The +14/+14 bp PBMC samples expressed higher levels of IL-10 when compared to the -14/+14 bp genotype and the -14/-14 bp genotype. Interestingly, the IL-10 G/G polymorphism at position -1082 was more frequent in the +14/+14 bp genotype (P=0.024, chi2 test). These results support an autocrine loop between HLA-G5/sHLA-G1 and IL-10 expression in activated PBMCs, which may result in higher IL-10 levels in +14/+14 bp HLA-G genotypes.

Embryonic soluble HLA-G as a marker of developmental potential in embryos

BACKGROUND

In human reproduction, embryo implantation is complex and poorly understood. At present, no single markers are used in routine treatment to assay biochemical functions of the human embryo. Soluble human leukocyte antigen-G (sHLA-G) could be considered a possible marker of embryo developmental potential. It is localized primarily on the extravillous trophoblast, making this antigen a potential mediator of immune interaction at the maternal-fetal interface during gestation.

METHODS

Soluble-HLA-G levels were evaluated by an enzyme-linked immunosorbent assay (ELISA) employing monoclonal antibody MEM-G9. It was evaluated in 318 media of single embryo cultures. We correlated the presence of sHLA-G with embryo morphology and the pregnancy obtained in that treatment cycle.

RESULTS

No correlation was found between embryo morphology and sHLA-G levels. Pregnancy was observed only when the medium of at least one transferred embryo contained sHLA-G. In 26 out of 66 patients, none of the obtained embryos showed any detectable sHLA-G molecules and no pregnancy occurred.

CONCLUSIONS

From our results, we propose sHLA-G as a potential marker of embryo development: the sHLA-G ELISA can be a useful biochemical assay in addition to embryo morphology in embryo selection for transfer in IVF treatment if there are other embryos with the same morphology.

Convulsive disorder and genetic polymorphism. Association of idiopathic generalized epilepsy with haptoglobin polymorphism

Haptoglobin is a polymorphic protein that is well known for its hemoglobin (Hb)-binding property. The protein shows gross differences in molecular size among genotypes, resulting in different degrees of diffusion in central nervous system tissue. Since the breakdown of erythrocytes in the intracerebral fluid results in Hb-mediated free OH radical formation, lipid peroxidation, and increased neuronal excitability, a differential diffusion of haptoglobin phenotypes in the intracerebral fluid might result in a different degree of protection from oxidative damage. We have studied two samples of children with idiopathic generalized epilepsy from two different Italian populations. In both samples the haptoglobin *1/*1 genotype is much less represented in epileptic children than in controls. These observations suggest that subjects carrying the Hp*1/*1 genotype, that has the lowest molecular size and diffuses more readily in the interstitial cerebral fluid, are more protected against idiopathic generalized epilepsy than those with other haptoglobin genotypes.

Enhanced P2X7 activity in human fibroblasts from diabetic patients: a possible pathogenetic mechanism for vascular damage in diabetes

OBJECTIVE

We have investigated expression and function of the P2X7 receptor in fibroblasts from healthy subjects and patients with type 2 diabetes.

METHODS AND RESULTS

Fibroblasts were isolated from skin biopsies. P2X7 receptor expression in both cell populations was measured by functional assays, RT-PCR, fluorescence-activated cell sorter, and immunoblotting. We found that fibroblasts from diabetic subjects are characterized by enhanced P2X7-mediated responses as indicated by increased shape changes, microvesiculation, enhanced fibronectin and interleukin 6 secretion, and accelerated apoptosis. These responses were blocked by preincubation with the P2X blockers KN-62, oxidized ATP, or pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid). Furthermore, we also found a higher level of spontaneous fibronectin secretion and of apoptosis in fibroblasts from diabetic compared with healthy subjects. Both higher basal level of fibronectin secretion and spontaneous rate of apoptosis were likely attributable to the increased pericellular concentration of ATP because fibroblasts from diabetic subjects released 3x as much ATP into the supernatants compared with fibroblasts from healthy subjects.

CONCLUSIONS

We conclude that fibroblasts from type 2 diabetes patients are characterized by a hyperactive purinergic loop based either on a higher level of ATP release or on increased P2X7 reactivity.

HLA-G and IL-10 in serum in relation to HLA-G genotype and polymorphisms

The expression and importance of the non-classical human leukocyte antigen (HLA) class Ib gene, HLA-G, at the feto-maternal interface have been recognized. The HLA-G molecule is almost monomorphic and expressed in both membrane-bound and soluble isoforms. It has been shown to inhibit NK-mediated cell lysis and influence cytokine expression. Recently, a possible boarder immunoregulatory function of HLA-G also in adult life has been recognized. HLA-G gene polymorphism has been linked to differences in gene expression profile of alternatively spliced HLA-G transcripts and levels of specific HLA-G mRNA isoforms. On this background it is of general interest to further elucidate any associations between HLA-G polymorphism and protein expression. We have HLA-G genotyped 85 individuals attending IVF treatment, and further studied sHLA-G1/HLA-G5 and interleukin-10 (IL-10) in serum samples. In 21% of the serum samples sHLA-G1/HLA-G5 could be detected. There was no correlation between sHLA-G1/HLA-G5 and IL-10 concentrations in serum. Soluble HLA-G1/HLA-G5 was not detected in any samples homozygous for a 14-bp insertion polymorphism in exon 8 of the 3'-untranslated region (3'UTR) of the HLA-G gene ( P=0.03; Fisher's exact test). Polymorphisms in the 5'-upstream regulatory region (5'URR) of the HLA-G gene were also studied. In conclusion, this study indicates that polymorphisms in the 3'UTR and the 5'URR of the HLA-G gene may influence the expression of sHLA-G of possible importance in pathological pregnancies and also in organ transplantation.

Beneficial effect of interferon-β 1b treatment in patients with relapsing–remitting multiple sclerosis is associated with an increase in serum levels of soluble HLA-I molecules during the first 3 months of therapy

It has recently become clear that interferon-beta (IFN-beta) treatment is effective in ameliorating relapsing-remitting multiple sclerosis (RRMS) through an as yet unidentified mechanism. As there is no recognisable biological indicator to predict responsiveness to IFN-beta treatment, we have investigated fluctuations in serum sHLA-I levels in MS patients undergoing IFN-beta 1b therapy. Serum sHLA-I concentrations measured by enzyme-linked immunosorbent assay (ELISA) were assessed at baseline and, longitudinally, over a period of 18 months after the start of treatment in 29 RRMS patients grouped as responders and nonresponders according to their clinical response to IFN-beta 1b therapy. Thirty-nine healthy volunteers served as controls. Serum sHLA-I concentrations were significantly higher (p<0.001) in pretreated RRMS patients than in healthy donors. In MS patients, changes in mean serum levels of sHLA-I from baseline showed a temporal pattern characterized by a strong increase in the first trimester of treatment, a return toward basal values in the following 6 months, a slight decline at 12th and 15th months and a further moderate increase at the 18th month. Mean serum sHLA-I levels were significantly more elevated in responders than in nonresponders at the first (p<0.02), second (p<0.01), and at third (p<0.02) months after the beginning of treatment and significantly lower (p<0.01) at the time of relapses in comparison to baseline values. Overall, these results seem to indicate that IFN-beta 1b can modulate fluctuations in serum sHLA-I levels and argue in favour of a potential role for serum levels of sHLA-I as a sensitive marker to monitor response to IFN-beta treatment in MS.

Presence of detectable levels of soluble HLA-G molecules in CSF of relapsing-remitting multiple sclerosis: relationship with CSF soluble HLA-I and IL-10 concentrations and MRI findings

We have investigated the presence of non-classical soluble HLA-G molecules (sHLA-G) in cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients and the possible relationships between CSF levels of sHLA-G, classical soluble HLA-I (sHLA-I) molecules, IL-10 amounts and Magnetic Resonance Imaging (MRI) findings were evaluated. We studied by ELISA technique the sHLA-I, sHLA-G and IL-10 levels in CSF of 50 relapsing-remitting (RR) MS patients stratified according to clinical and MRI evidence of disease activity. Thirty-six patients with other inflammatory neurological disorders (OIND) and 41 with non-inflammatory neurological disorders (NIND) were used as controls. CSF mean levels were significantly higher in MS and OIND than in NIND for sHLA-I (p<0.001) and in MS than in controls for sHLA-G (p<0.001), with no differences among the various groups for IL-10 mean concentrations. An increase in CSF sHLA-I was found in MS patients with Gd-enhancing lesions (p<0.01), while sHLA-G and IL-10 were more represented in MS patients without lesional activity on MRI scans (p<0.02). In MRI-inactive MS, CSF IL-10 mean concentrations were significantly greater in patients with CSF-detectable levels of sHLA-G than in those without any evidence of CSF sHLA-G expression (p<0.05). Our findings suggest that CSF classical sHLA-I and non-classical sHLA-G levels may modulate MS activity as assessed by MRI acting in opposite directions. The association observed between sHLA-G and IL-10 when Gd-enhancing lesion resolved indicates a potential immunoregulatory role for IL-10 in the control of MS disease activity by shifting the sHLA-I/sHLA-G balance towards sHLA-G response.

Human leukocyte antigen-A, -B, -C and -DR alleles and soluble human leukocyte antigen class I serum level in Ménière's disease

Previous studies have suggested that many human leukocyte antigen (HLA)-A, -B, -C and -DR alleles are associated with Ménière's disease (MD), an inner ear disorder with a proposed autoimmune etiopathogenesis. Despite some discrepancies many reports are in agreement with a hypothesis suggesting an influence of serologically detected HLA-C products in the susceptibility to the disease. To confirm these data we investigated the distribution of HLA-A, -B, -C and -DR antigens that well define the HLA polymorphism using DNA typing. Furthermore, as autoimmune factors have been claimed to play a role in MD, we investigated the serum level of soluble HLA class I (sHLA-I). Molecular typing of HLA class I and II was performed using polymerase chain reaction sequence-specific primers in 41 patients affected by MD, 34 patients affected by other inner ear diseases (OIDs) and 101 healthy subjects. An ELISA technique was employed to investigate the serum level of sHLA-I in 17 MD patients, 10 OID patients and 83 healthy subjects. The results showed a significantly increased frequency of the Cw*07 specificities in MD patients when compared to OID patients (63.4% vs 32.3%; p = 6.9 x 10(-3); relative risk [RR] = 3.6) and healthy subjects (63.4% vs 35.6%; p = 2.28 x 10(-3); RR = 3.1). The sHLA-I concentrations detected in sera did not differ significantly between MD patients (616 +/- 271 ng/ml), OID patients (570 +/- 307 ng/ml) and healthy subjects (518 +/- 340 ng/ml).

Clinical and MRI disease activity in multiple sclerosis are associated with reciprocal fluctuations in serum and cerebrospinal fluid levels of soluble HLA class I molecules

The goal of our study was to clarify the contribution of soluble human leukocyte antigens class I (sHLA-I) in multiple sclerosis (MS) immune dysregulation. We retrospectively evaluated by ELISA cerebrospinal fluid (CSF) and serum sHLA-I levels in 79 relapsing-remitting (RR), 26 secondary progressive (SP) and 15 primary progressive (PP) MS patients stratified according to clinical and Magnetic Resonance Imaging (MRI) evidence of disease activity. One hundred and nine patients with other inflammatory neurological disorders (OIND), 88 with noninflammatory neurological disorders (NIND) and 82 healthy donors were used as controls. An intrathecal synthesis of sHLA-I detected by a specific index was significantly more consistent in MS than in controls, with more pronounced values in MS patients with relapses and MRI enhancing brain lesions. A decrease in serum sHLA-I concentrations was observed in MS patients with demyelinating attacks, while an increase in CSF levels of sHLA-I was found in MS patients with lesional activity on MRI scans. This association between intrathecal synthesis and reciprocal fluctuations of CSF and serum levels of sHLA-I in clinically and MRI active MS seems to suggest a potential role for CSF and serum levels of sHLA-I as a sensitive marker of immune activation taking place both intrathecally and systemically in MS.

HLA-G expression in early embryos is a fundamental prerequisite for the obtainment of pregnancy

Different mechanisms mediated by the expression of the HLA-class Ib HLA-G products are suggested to account for the induction of immune tolerance against the paternal antigens of the fetus during pregnancy. Soluble HLA-G antigens, mainly produced by cytotrophoblast cells at the materno-fetal interface and circulating in the body fluids, show a capacity analogous to that of membrane-boundstructures to inhibit NK cells. In the present report we have investigated, using specific ELISA, the presence of sHLA-G molecules in culture supernatants of early embryos obtained by in vitro fertilization (IVF) before transfer. The data obtained from the analysis of 285 supernatants corresponding to 101 IVF procedures (43 IVF, 58 intracytoplasmic sperm injection) identify two groups of patients on the basis of sHLA-G antigen presence. No differences in clinical parameters were observed between the groups, but positive embryo implantations occurred only in women showing sHLA-G molecules in culture supernatants (Fisher's exact p value 2.56 x 10(-3)). The results obtained indicate that expression of HLA-G products in embryo cells is a mandatory, but not sufficient, prerequisite for the development of pregnancy.

Molecular dynamics study on the conformational stability of laminaran oligomers in various solvents

Solution conformations of the (1-->3)-beta-D-glucan laminaran have been investigated by means of molecular mechanics and molecular dynamics simulations in three solvents: water, dimethylformamide, and dimethyl sulfoxide. Conformational analysis of solvated laminarabiose was carried out to study the effect of specific solute-solvent interactions upon reactive hydroxyl groups. Dynamic trajectories of solvated laminarabiose have been interpreted in terms of average glycosidic-linkage conformation, hydrogen-bonding pattern, and coordination by solvent molecules. The analysis of radial distribution functions, coordination functions, mean residency times, and time correlation functions derived from the simulation trajectories furnished the necessary insight. The results have been used to assess the steric accessibility of laminaran-C4-OH and -C6-OH hydroxyl groups in the considered solvents and to rationalize corresponding earlier experimental observations. The experiments demonstrated that reaction equilibrium during chemical modification of laminaran oligomers with 2,2-dimethoxypropane involving the laminaran-C4-OH and -C6-OH hydroxyl groups significantly depended on the solvent used.

Divalent cation interactions with oligogalacturonides

The conformational properties of high and low molecular weight galacturonides were investigated in relation to the ability of oligomers with degree of polymerization >10 to act as elicitors of plant defense mechanisms. Oligomers from polygalacturonate were obtained by means of enzymatic hydrolysis. Two fractions exhibiting high and low average degrees of polymerization were isolated by solvent fractionation and characterized by means of electrospray mass spectrometry. The conformational behaviors of the two fractions were investigated in the presence of different divalent cations using circular dichroism. Calcium, copper, and zinc ions were able to induce a conformational transition in both fractions. When in the presence of the high molecular weight fraction, copper and zinc ions were much more effective than calcium ions, whereas the efficiency was much reduced with low molecular weight oligomers.

Host-guest complex formation in cyclotrikis-(1-->6)

The possibility that cyclotrikis-(1-->6)-[alpha-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl] (CGM6) forms inclusion complexes, like cycloamyloses (cyclodextrins), was investigated by means of electrospray mass spectrometry and fluorescence spectroscopy. The complexing ability of both 1-anilinonaphthalene-8-sulfonate (ANS) and 2-p-toluidinylnaphthalene-6-sulfonate (TNS), which were already used with cyclodextrins, was investigated. The former showed very little or no tendency to be complexed by CGM6, while the latter produced detectable adducts with CGM6. Fixed 90 degree angle light scattering experiments supported the findings obtained by molecular modelling calculations, which indicated a polar character for the CGM6 internal cavity. CGM6-TNS complexes were probably formed throughout interaction of the polar regions of the two molecules.

Collagen fibrils are differently organized in weight-bearing and not-weight-bearing regions of pig articular cartilage

The magnetic resonance (MR) appearance of the weight-bearing ("loaded") and not-weight-bearing ("unloaded") regions in T(2)-weighted images of pig articular cartilage is different. On the hypothesis that this difference may be ascribed, at least in part, to a different collagen fibre organization in the two regions, this organization was studied using biochemical, histological, and X-ray diffraction methods. While the mean concentrations of collagen and of its cross-links were the same in the two regions, a regular small angle X-ray diffraction pattern was observed only for the habitually "loaded" tissue. It was also seen by light microscopy that the four typical functional zones were well displayed in the "loaded" cartilage whereas they were not clearly depicted in the "unloaded" tissue. Collagen presented a high concentration of fibrils forming an intricate and dense meshwork at the surface of both "loaded" and "unloaded" cartilage. A second zone of high collagen concentration was present at the upper layer of the deep zone of "loaded" cartilage. By contrast, this lamina of highly concentrated fibrils was lacking in "unloaded" cartilage and collagen fibrils appear thinner. Our study proves that the organization of collagen fibres is different for the "loaded" and "unloaded" regions of articular cartilage. It also suggests that this different organization may influence the MR appearance of the tissue. J. Exp. Zool. 287:346-352, 2000.

The Personal Health Questionnaire: a new screening instrument for detection of ICD-10 depressive disorders in primary care

BACKGROUND

The next generation of studies on antidepressant drug prescriptions in general practice needs to assess both the patterns of prescription and its appropriateness. This study aimed to assess the performance of the Personal Health Questionnaire (PHQ), a new questionnaire for detecting individuals with ICD- 10 depressive disorders, to be used in association with companion instruments for assessing the 'quality' of antidepressant prescriptions in primary care settings.

METHODS

The PHQ was completed by 1,413 primary care attenders (100 were re-tested after 7-14 days) and 139 were selected and interviewed using the SCAN-2 and the 17-item HDRS. All data were analysed using appropriately weighted procedures to control for two-phase sampling design and non-response bias. Individual weights were estimated by logistic regression analysis and trimming strategy.

RESULTS

PHQ internal consistency and test-retest on both Likert score and number of symptoms were high. The PHQ discriminated well between individuals with and without depressive disorders. A Likert score > or = 9 provided a good trade-off between sensitivity (0.78) and specificity (0.83). The screening accuracy of the PHQ in detecting subjects likely to benefit from antidepressant drug treatment (SCAN cases with a HDRS total score of 13 or higher) was satisfactory (ROC area 0.87: sensitivity 0.84; specificity 0.78).

CONCLUSIONS

The PHQ can be strongly suggested as an accurate and economic screener to identify primary care attenders at high risk of being clinically depressed. However, in order to identify patients requiring antidepressant drug treatment, a second-phase assessment of PHQ high scorers (total score of > or = 10), using the HDRS, is needed.

Diffuse polymicrogyria associated with congenital hydrocephalus, craniosynostosis, severe mental retardation, and minor facial and genital anomalies

We report an infant boy with an apparently new malformation syndrome. The major anomalies showed by the patient include diffuse polymicrogyria, congenital hydrocephalus, craniosynostosis with severe scaphocephaly, severe mental retardation, intractable epilepsy, and minor facial and genital anomalies. Our review of the literature and two computerized dysmorphology databases found some papers reporting polymicrogyria or lissencephaly associated with craniosynostosis or hydrocephalus. None of the reported patients had a phenotype similar to that of our patient.

Articular cartilage repair in rabbits by using suspensions of allogenic chondrocytes in alginate

The feasibility of allogenic implants of chondrocytes in alginate gels was tested for the reconstruction in vivo of artificially full-thickness-damaged articular rabbit cartilage. The suspensions of chondrocytes in alginate were gelled by the addition of calcium chloride solution directly into the defects giving in situ a construct perfectly inserted and adherent to the subchondral bone and to the walls of intact cartilage. The tissue repair was controlled at 1, 2, 4 and 6 months after the implant by NMR microscopy, synchrotron radiation induced X-ray emission to map the sulfur of glycosaminoglycans and by histochemistry. Practically a complete repair of the defect was observed 4-6 months from the implant of the chondrocytes with the recovery of a normal tissue structure. Controls in which Ca-alginate alone was implanted developed only a fibrous cartilage.

Biocompatibility in vitro of titanium dental implants. Immunocytochemical expression of fibronectin and extracellular matrix receptors

BACKGROUND

Cell-substratum interactions play a peculiar role in cell proliferation, differentiation and migration. They are regulated by various glycoproteins, among which fibronectin, and by receptors connecting cells to the extracellular matrix, i.e. integrins. Therefore, the aim of this study was to correlate the proliferation rates of the human fibroblast line WI-38 cultured in presence of titanium dental implants to cell adhesion capability to substrata.

METHODS

WI-38 fibroblasts were cultured in presence of four dental implants in titanium (one hydroxyapatite coated) for 48, 72 and 96 hours. Cell proliferation was evaluated by detecting 5-bromodeoxyuridine incorporation. Fibronectin organization and alpha5beta1 integrin expression were evidenced by indirect immunofluorescence.

RESULTS

A correlation between fibronectin organization and cell proliferation rates was demonstrated: cultures showing fibronectin mainly organized in fibrils presented the highest cell proliferation degrees. After 96 hours, the observed decrease of the number of proliferating cells corresponded to a different fibronectin organization. In presence of the hydroxyapatite coated implant, colocalization of fibronectin and alpha5beta1 integrin was represented in focal contacts in cultures exhibiting the highest proliferation rate, while cells with the lowest proliferation one expressed alpha5beta1 integrin in point contacts.

CONCLUSIONS

Evidences obtained in this work showed that both the organization of fibronectin and the expression of alpha5beta1 integrin are strictly correlated to cell proliferation rates. Therefore, these parameters could be useful for evaluating the biocompatibility of dental materials in vitro.