Effect of interfacial surface treatment on bond strength of particulate-filled composite to short fiber-reinforced composite.

Objective: The aim was to investigate the effect of different interfacial surface treatments on the shear bond strength (SBS) between a short fiber-reinforced flowable composite (SFRC) and a particulate-filled flowable composite (PFC). In addition, SBS between two successive layers of similar materials was evaluated. Materials and methods: One-hundred and forty-four specimens were prepared having either SFRC (everX Flow) as a substructure composite and PFC (G-aenial Flo X) as a surface composite or having one of the two materials as both substructure and surface layer. Eight groups of specimens were created (n = 18/per group) according to the interfacial surface protocol used. Group 1: no treatment; Group 2: ethanol one wipe; Group 3: ethanol three wipes; Group 4: phosphoric acid etching + bonding agent; Group 5: hydrofluoric acid etching + bonding agent; and Group 6: grinding + phosphoric acid etching. Group 7: only PFC layers and Group 8 (control) only SFRC layers without any surface treatment. After one-day storage (37 °C), SBS between surface and substructure composite layers was measured in a universal testing machine, and failure modes were visually analyzed. SEM was used to examine the bonding surface of the SFRC composite after surface treatment. SBS values were statistically analyzed with a one-way analysis of variance (ANOVA) followed by the Tukey HSD test (α = .05). Results: The SBS between successive SFRC layers (Group 8) was statistically (p < .05) the highest (43.7 MPa) among tested groups. Surface roughening by grinding followed by phosphoric acid etching (Group 6) resulted in a higher SBS (28.8 MPa) than the remaining surface treatments. Conclusion: Flowable composite with glass fibers (everX Flow) showed higher interlayer SBS compared to PFC flowable composite. Interfacial surface roughness increases the bonding of PFC to the substructure of SFRC.

HLA-DR-DQ haplotypes and genotypes in Finnish patients with rheumatoid arthritis.

OBJECTIVES: To elucidate the contribution of HLA-DR-DQ haplotypes and their genotypic combinations to susceptibility to rheumatoid arthritis, and to evaluate the various models for HLA associated risk for the disease in a series of Finnish patients. METHODS: 322 Finnish patients with rheumatoid arthritis were typed for common north European HLA-DR-DQ haplotypes and compared with a series of 1244 artificial family based control haplotypes. RESULTS: The association of the so called shared epitope (SE) haplotypes (DRB1*0401, *0404, *0408, and *01) with rheumatoid arthritis was confirmed. The DRB1*0401 haplotypes carried a far stronger risk for the disease than the (DRB1*01/10)-(DQA1*01)-DQB1*0501 haplotypes. Seven protective HLA haplotypes--(DRB1*15)-(DQA1*01)-DQB1*0602; (DRB1*08)-(DQA1*04)-DQB1*04; (DRB1*11/12)-DQA1*05-DQB1*0301; (DRB1*1301)-(DQA1*01)-DQB1*0603; (DRB1*1302)-(DQA1*01)-DQB1*0604; (DRB1*07)-DQA1*0201-DQB1*0303; and (DRB1*16)- (DQA1*01)-DQB1*0502--were identified. In accordance with the reshaped shared epitope hypothesis, all the protective DRB1 alleles in these haplotypes share either isoleucine at position 67 or aspartic acid at position 70 in their third hypervariable region motif. However, differences in the disease risk of haplotypes carrying the same DR but different DQ alleles were also found: (DRB1*07)-DQA1*0201-DQB1*0303 was protective, while (DRB1*07)-DQA1*0201-DQB1*02 was neutral. The same haplotypes carried different risks for rheumatoid arthritis depending on their combination in genotypes. CONCLUSIONS: When assessing the influence of HLA genes on the susceptibility to rheumatoid arthritis, not only should the HLA-DR or -DQ alleles or haplotypes be unravelled but also the genotype. The effect of HLA class II region genes is more complicated than any of the existing hypotheses can explain.

HLA haplotype analysis in Finnish patients with rheumatoid arthritis.

OBJECTIVE: To further characterize the HLA gene products that play an important role in the pathogenesis of rheumatoid arthritis (RA). METHODS: One hundred thirty-four haplotypes from 67 Finnish RA patients and 77 control haplotypes were analyzed for HLA-DRB1 loci, associated alleles of the HLA-DQB1 locus, alleles of the type 2 transporter-associated antigen processing (TAP2) genes, and HLA-B27. In addition, a panel of microsatellite markers within the HLA class I and class III regions was studied. RESULTS: The frequency of HLA-DRB1*04 in the haplotypes of RA patients was found to be 34% (45 of 134) compared with 14% (10 of 72) in control haplotypes (P = 0.004). The frequency of HLA-DRB1*13 was decreased in RA haplotypes (4%, or 5 of 134) in contrast to control haplotypes (24%, or 17 of 72) (P = 0.000031). The decrease in DRB1*13 was not secondary to the increase in DRB1*04, since it was also found among DRB1*04-negative haplotypes (P < 0.001). The DRB1*13-associated DQB1*0604 allele was similarly decreased in RA haplotypes (P = 0.025). The TAP2I allele of I/J dimorphism was increased in RA patients (85%, or 114 of 134) as compared with controls (69%, or 49 of 71) (P = 0.011). Of the tumor necrosis factor (TNF) microsatellite alleles, TNFa6 and TNFb5 were found to be increased in RA haplotypes (for a6 27% versus 5% in controls [P = 0.00043], and for b5 43% versus 26% in controls [P = 0.037]). CONCLUSION: Both protection-associated and susceptibility-associated alleles can be found among HLA class II genes, and the results suggest that loci outside DR/DQ may contribute to the pathogenesis of RA.

Immunogenetic differences between patients with familial and non-familial rheumatoid arthritis.

OBJECTIVE: To search for possible immunogenetic differencies between the patients with familial and non-familial rheumatoid arthritis (RA). METHODS: The study compared 129 familial RA patients with 217 non-familial patients for the frequencies of HLA-DR antigens including DR4 subtypes, DR4-DQB1*0301 and DR4-DQB1*0302 haplotypes and HLA-B27 antigen as well as the age of disease onset and existence of rheumatoid factor or joint erosions. RESULTS: Two major differences between familial and non-familial groups were found: firstly, familial RA patients had increased frequency of HLA-DR4 as compared with the non-familial RA group (68.2 v. 54.8%; p = 0.019). Secondly, the mean age at onset of RA was significantly lower in the familial than in the sporadic RA patients (42.0 v. 46.5 years; p = 0.0020) and the difference still remained when the DR4 positive and negative subgroups were compared separately. CONCLUSION: These results confirm the more prominent association with HLA-DR4 in familial than in the non-familial cases and suggest that accumulation of HLA risk genes may, at least partly, explain the familial occurrence of the disease. Other susceptibility genes may also be concentrated in multiplex case families as suggested by an earlier age at the onset of RA in both HLA-DR4 positive and negative familial patients.

Tumour necrosis factor microsatellites in reactive arthritis.

The purpose was to study tumour necrosis factor (TNF)-a, -b and -c microsatellites as potential new susceptibility markers for reactive arthritis (ReA). Fifty-nine patients typed for HLA-B27 were studied for frequencies of TNF microsatellite alleles and compared with allele frequencies determined from 285 random haplotypes and 46 healthy HLA-B27-positive controls. TNFa, -b and -c microsatellite sequences were amplified by the polymerase chain reaction, and the size of the product was defined by an automated sequencer. The frequencies of TNFa6 and -c1 alleles were found to be increased in patients with ReA, whereas TNFa11 and -c2 frequencies were decreased as compared to control haplotypes. The increase in the c1 allele in patients with ReA independently from HLA-B27 suggests that it might be a new susceptibility marker for the disease. The association of ReA with other alleles was due to a linkage disequilibrium with HLA-B27.

TAP2 alleles in inflammatory arthritis.

Sixty patients with reactive arthritis (ReA) and 40 with rheumatoid arthritis (RA), were typed for H LA-B27 and class II antigens DR and DQ, and studied for TAP2 gene polymorphism in comparison with 60 healthy controls. TAP2 polymorphisms at positions 379, 565, 665, and 687 were analyzed using amplification refractory system-based PCR and polymorphisms at positions 386 and 651 using oligonucleotide hybridization. The frequency of the TAP2A/A genotype was 30%(12/40) in RA, in contrast to 13% (8/60) in the controls. This genotype was further associated with DRB1*04 positive RA (10/24, 42%, P=0.01), as well as the TAP2A allele (31/48, 65%, P =0.012). Thr/Thr dimorphism at TAP2 position 665 (24/40, 60%, P=0.024) and Stop/Stop dimorphism at TAP2 position 687 (24/40, 60%, P=0.024) were found to be increased in RA patients as compared to controls. When TAP2I/J polymorphism was studied, TAP2J positivity was found associated with the HLA-B27DR4-DQB1*0301-haplotype in ReA patients. 9/12 of these were positive as compared to 20/60 in random controls (P=0.010). Polymorphisms of the TAP2 gene were found to be associated with subgroups of RA and ReA patients with disease associated markers (e.g. TAP2A in DRB1*04 positive RA, or TAP2J in HLA-B27-DRB1*04-DQB1*0301 positive ReA). These may thus serve as additional markers of specific haplotypes associated with susceptibility to inflammatory arthritis.

Increase of HLA-DRB1*0408 and -DQB1*0301 in HLA-B27 positive reactive arthritis.

OBJECTIVE: To study HLA class II association in reactive arthritis. METHODS: 63 patients with reactive arthritis and 46 with rheumatoid arthritis were included in the study. HLA-DR alleles were determined by using a sequence specific PCR method. Oligonucleotide hybridisation was used for definition of DRB1*04 subtypes and DQB1 alleles. HLA-B27 was determined by standard microcytotoxity test or by PCR. HLA-B27 subtyping was made by sequencing. RESULTS: 46 (73%) of 63 patients with reactive arthritis were HLA-B27 positive and 24 (38%) were HLA-DRB1*04 positive. When haplotypes were inferred according to the known associations between DRB1 and DQB1 alleles, the frequency of DRB1*04-DQB1*0301 haplotype was found to be 13% (12/92) in HLA-B27 positive reactive arthritis patients, in contrast to 0% in HLA-B27 negative reactive arthritis (P = 0.04) and 1% in random controls (P = 0.0009). However, this combination was also found in 5% of 84 HLA-B27 positive control haplotypes, showing a linkage disequilibrium between B27 and this particular class II haplotype. HLA-DRB1*0408 subtype was found in 8/24 (33%) of the HLA-DRB1*04 alleles in patients with reactive arthritis, accounting for most DQB1*0301 haplotypes, but only in 5/55 (9%) of the DRB1*04 alleles in random controls (P = 0.017). All reactive arthritis patients with this subtype were positive for HLA-B27. DRB1*04-DQB1*0302 haplotype was increased in patients with rheumatoid arthritis (28/92, 30%) compared with reactive arthritis (12/126, 10%) or with the controls (12/100, 12%; P = 0.003). HLA-B*2705 was by far the dominant B27 subtype both in reactive arthritis patients with the particular DRB1*0408-DQB1*0301 haplotype and in controls. It was found in 11 out of 12 DR analysed patients, as well as in 10 out of 11 randomly selected B27 positive controls. CONCLUSIONS: Although no single class II allele was found to be increased among patients with reactive arthritis, HLA-B27, DRB1*0408, and DQB1*0301 might exert a haplotypic effect in the pathogenesis of reactive arthritis, or they may be markers of a subset of B27 haplotypes conferring susceptibility.

HLA-DR4 subtype and -B alleles in DQB1*0302-positive haplotypes associated with IDDM. The Childhood Diabetes in Finland Study Group.

We determined the distribution of DR4 subtypes in 309 DQB1*0302-positive haplotypes found in insulin-dependent diabetes mellitus (IDDM) patients and 70 control haplotypes present only in healthy family members. An increased frequency of DRB1*0401 allele (74.4% vs. 55.7%, P = 0.003) and a decrease of DRB1*0404 allele (23.6% vs. 40.0%, P = 0.0064) was revealed. A further analysis of extended haplotypes demonstrated strong linkages between various B alleles and DRB1*04 subtypes. HLA-B39 was more frequent in DRB1*0404-DQB1*0302-positive IDDM haplotypes compared with control ones (37.0% vs. 14.3%, P = 0.049), suggesting an involvement of the region telomeric to HLA-DRB1 in the susceptibility to IDDM.

HLA frequencies in HLA-B27 negative patients with reactive arthritis.

The purpose of the present work was to find out whether there is an HLA type common to the patients who, in spite of being B27 negative, have developed reactive arthritis (ReA). We compared the HLA-antigens of 25 HLA-B27 negative ReA patients to those of healthy control persons. No statistically significant differences were observed in the HLA-A, B, C, DR and DQ antigen frequencies between the patients and the control group. The frequency of DR4 was slightly lower in the patients than in the controls, although this difference was not statistically significant. On the other hand, 18/25 (72%) of the B27-negative ReA patients experienced a chronic or prolonged course of the disease. These findings indicate that DR4 does not contribute to the chronicity of ReA in the same way that it is known to do in rheumatoid arthritis (RA) or Lyme arthritis. They do not support the hypothesis that some other HLA-antigen, in addition to HLA-B27, could have a predisposing or protective effect in ReA.