Multiple etchings methodology: a new approach in multiphase steel characterization.

Following the first and second generations, the challenge in obtaining a better balance between strength and elongation is still the main characteristic of the third generation of advanced high-strength steels (AHSS). With this, the use of multiphase microstructures has increased over the last few years. It can be difficult to characterize all the phases with only optical microscopy (OM), so the use of scanning electron microscopy (SEM) is essential for accuracy in cases where researchers lack experience. To expand the possibilities, this research proposed a new approach that would allow experienced researchers to characterize multiphase steels using only OM. A high silicon steel was austempered slightly below martensite start (Ms) temperature for three different time periods in order to obtain different quantities of martensite, bainite and retained austenite. X-ray diffraction was carried out in order to confirm and obtain retained austenite volume fractions, and the results indicated that shorter holding times were not enough to enrich and stabilize retained austenite. Then, each samples was etched with four different etchants. Results showed that the new multiple etchings methodology (MEM) allowed a better visualization of all the phases when viewed together. Beraha martensitc revealed nontempered martensitic microstructures. Sodium metabisulfite revealed retained austenite. LePera and Nital were the best at revealing the evolution of the microstructure over time, even with the changes which occurred due to martensite tempering. SEM images confirmed the results obtained via MEM. LAY DESCRIPTION: For improving safety, environmental protection, mechanical resistance and others issues, many different steel grades have been studied. These grades were named depending on their mechanical properties. The current generation is the third, which is still searching for one of the main antagonists in material science: the best balance between mechanical resistance (how strong it is) and elongation (how long it can be stretched to). In order to achieve this goal, many researchers are studying variations in the production processes. During production, the materials are able to internally change their basic microstructure, named phases. In the past, steels were usually produced to have only a few phases. Today's advanced high strength steels (AHSS) can have many. Each of these phases has its own characteristics. The main focus of this research was to give a new way of identify these phases using an optical microscope. For revealing these phases, etchants are normally used. The etchants used in this research are capable of tinting each of these phases with a different colour or tone. So the purpose of this work was to suggest a new approach in order to allow for more precise identification of the phases in the steel. The results were positive, showing that looking at the samples as a whole is better than the traditional methods. Also, different etchants' characteristics were observed during the changes obtained by this work's chosen processes.

MicroMegascope.

Atomic force microscopy (AFM) allows us to reconstruct the topography of surfaces with resolution in the nanometer range. The exceptional resolution attainable with the AFM makes this instrument a key tool in nanoscience and technology. The core of a standard AFM set-up relies on the detection of the change of the mechanical motion of a micro-oscillator when approaching the sample to image. This is despite the fact that AFM is nowadays a very common instrument for both fundamental and applied research. The fabrication of the micrometric scale mechanical oscillator is still a very complicated and expensive task requiring dedicated platforms. Being able to perform AFM with a macroscopic oscillator would make the instrument more versatile and accessible for an even larger spectrum of applications and audience. Here, we present atomic force imaging with a centimetric oscillator, an aluminum tuning fork of centimeter size as a sensor on which an accelerometer is glued on one prong to measure the oscillations. We show that it is possible to perform topographic images of nanometric resolution with a gram tuning fork. In addition to the stunning sensitivity, we show the high versatility of such an oscillator by imaging both in air and liquid. The set-up proposed here can be extended to numerous experiments where the probe has to be heavy and/or very complex, and so too the environment.

Application of a recombinant protein for the serological diagnosis of canine leishmaniasis.

This work reports the results obtained by a new enzyme-linked immunosorbent assay (ELISA) test developed for the serological diagnosis of canine leishmaniasis. The new ELISA is based on a recombinant protein obtained by joining different antigens of Leishmania infantum. Test performances have been evaluated through the screening 227 sera of dogs, infected and uninfected by L. infantum. The new ELISA test has been compared to the indirect immunofluorescent-antibody test (IFAT) as a reference assay of canine leishmaniasis, and to a commercial ELISA. Excluding from the total number of IFAT positive sera the 27 sera with IFAT titre 1:40 (considered doubtful), the recombinant ELISA showed 97.0% specificity, 93.9% sensitivity and 95.5% agreement with IFAT. The commercial ELISA showed 78.2% specificity, 94.9% sensitivity and 86.5% agreement with IFAT. The results demonstrate a higher performance of the new recombinant ELISA test for the detection of negative samples, with a greater agreement with the reference test (IFAT).

Are HLA class II and immunoglobulin constant region genes involved in the pathogenesis of mixed cryoglobulinemia type II after hepatitis C virus infection?

BACKGROUND/AIMS: Hepatitis C virus infection is known to play an important role in the pathogenesis of essential mixed cryoglobulinemia type II. Progression of hepatitis C virus infection to mixed cryoglobulinemia may be influenced by host immune response. To analyze the immunogenetic background of mixed cryoglobulinemia, we studied HLA-DR, DQ loci and the switch regions of immunoglobulin heavy chain gamma1 and gamma4 constant genes. METHODS: HLA typing was performed in 84 hepatitis C virus-infected patients (46 with cryoglobulins and 38 without), and 109 healthy controls, through analysis of restriction fragment length polymorphisms, supplemented with other techniques. Immunoglobulin heavy chain gamma1 and gamma4 polymorphisms, detected by restriction fragment length polymorphisms, were studied in 41 patients with mixed cryoglobulinemia and 51 controls. RESULTS: The gene frequency of DRB1*11 was significantly higher in patients with mixed cryoglobulinemia than in controls (0.36 and 0.20, respectively; p= 0.0035). However, DRB1*11 was also increased in the subgroup of patients without mixed cryoglobulinemia who did not develop severe liver disease, while it was decreased in those with severe liver damage (0.50 and 0.13; p=0.0035). The frequency of 5.4 kb allele of the immunoglobulin heavy chain gamma1 switch region was higher in patients with mixed cryoglobulinemia than in controls (0.47 and 0.22; pc=0.002), while the frequency of 5.5 kb allele was lower (0.51 and 0.78; pc= 0.001). CONCLUSIONS: Susceptibility to develop cryoglobulins after hepatitis C virus infection was not associated with HLA-DR or DQ. HLA-DRB1*11-positive individuals were protected from serious chronic liver disease after hepatitis C virus infection. Immunoglobulin heavy chain constant gamma1 switch region restriction fragment length polymorphisms were associated with mixed cryoglobulinemia.

Immunogenetics of Henoch-Schoenlein disease.

In order to investigate the genetic basis of susceptibility to Henoch-Schoenlein purpura (HS), blood samples of 152 patients, 105 of whom had renal disease, were collected in a two-step study. The evaluation of DRB, DQB and DQA polymorphism was done by analysis of the restriction polymorphisms produced by TaqI enzyme. DRB1*07 was less frequent in patients than in the control group (gene frequency 0.09 and 0.18, respectively; P = 0.0023), whereas 64% of the patients were positive for DRB1*01 and/or DRB1*11 compared with 48% of the control group (P = 0.0069). Polymerase chain reaction-sequence-specific oligonucleotide (PCR-SSO) typing of DRB1*01- and DRB1*11-positive individuals did not show any deviation of frequencies of DRB1*01 subtypes between patients and controls, whereas among DRB1*11 subtypes DRB1*1104 was significantly increased in the patients (Pc = 0.033). The comparison between patients with renal disease and those without renal disease showed no significant differences in the frequency of the single DRB, DQB and DQA alleles. The study of restriction polymorphisms in the switch region of the constant genes alpha 1, alpha 2 and mu of the heavy chains of immunoglobulins, using the enzyme Sacl and a specific probe, did not show any difference between 44 patients and 54 controls. This study demonstrates that susceptibility to HS also has a genetic origin: on one hand, the presence of DRB1*01 or DRB1*11 makes disease onset easier; on the other hand, DRB1*07 could induce some resistance to the disease. It is suggested that, as well as for other diseases caused by an impaired immune response, single amino acids in a key position in the HLA-DRB molecule make it more or less easy to recognize some antigenic peptide, towards which an immune response leading to disease is triggered.

Human leukocyte antigen class II polymorphisms and genetic susceptibility of IDDM in Egyptian children.

OBJECTIVE: To analyze the association between human leukocyte antigen (HLA) and insulin-dependent diabetes mellitus (IDDM) in the Egyptian population for the first time and, thus, to determine the frequency of risk-associated alleles identified by a genomic HLA class II typing. Egyptians are genetically classified as North Africans and considered to be between Caucasoids and Africans (closer to Caucasoids). RESEARCH DESIGN AND METHODS: HLA class II typing was performed for 50 IDDM patients and 50 healthy control subjects by a restriction fragment-length polymorphism (RFLP) technique. The analysis of position 57 of the DQB1 molecules was conducted by polymerase chain reaction and specific sequence oligonucleotide hybridization. RESULTS: The frequency of DRB1*0301-DRB3*0201-DQA1*0501-DQB1*0201 haplotype was 43.9% in the IDDM patients and 7.1% in the control subjects (P < 0.00001), reflecting the increased prevalence of DQA1*0501 susceptibility allele coding for arginine (Arg) in position 52 and DQB1*0201 susceptibility allele non-coding aspartic acid (Asp) at position 57. Alleles DQB1*0601 and 0603, both carrying Asp at position 57 of the beta-chain, and DQA1*0103, encoding a non-Arg 52 alpha-chain, were significantly decreased among the IDDM patients. The presence of four susceptibility residues (two DQA1 Arg 52+ and two DQB1 Asp 57-) conferred the highest relative risk at 20.2. On the other hand, homozygous genotypes for DQA1 non-Arg 52 and DQB1 Asp 57 were found only in the control group. CONCLUSIONS: IDDM susceptibility and resistance in the Egyptian population is strongly associated with the expressed DQ alpha- and beta-heterodimers in a dose-effective manner, as already defined in many different ethnic groups.

Familial occurrence of primary glomerulonephritis: evidence for a role of genetic factors.

Chronic glomerulonephritis was diagnosed in 23 patients born in a small valley in Northern Italy and in five additional patients with one parent or a more remote ancestor born in the same area, all belonging to three potentially related families. Eighteen patients had biopsy-proven glomerulonephritis: 11 IgA nephropathy, 3 IgM nephropathy, 2 membranoproliferative type I, and 2 mesangial proliferative glomerulonephritis with isolated C3 deposits. Ten had clinical glomerulonephritis. A community screening programme discovered six additional related patients. Two underwent renal biopsy (1 IgA nephropathy; 1 focal glomerulosclerosis); four were diagnosed as having clinical glomerulonephritis. Genealogical investigation identified five deceased family members with diagnoses of chronic nephritis recorded on their death certificates. No environmental nephrotoxic factors were identified. Restriction fragment length polymorphism (RFLP) analysis of HLA-DR beta, HLA-DQ alpha and beta genes, and complement typing for C4A, C4B, and Bf polymorphisms were carried out for 29 patients, 168 healthy relatives, and 24 local controls. The frequency of HLA-Dw8.1 specificity, related to DR beta 8, DQ beta 3b, and DQ alpha 1a RFLPs, was significantly increased more in the affected and unaffected pedigree members than in Italian controls.

Loss of heterozygosity on chromosome 17p13 in breast carcinomas identifies tumors with high proliferation index.

The capacity of breast tumor cells to proliferate is considered a potential prognostic factor together with other histopathologic parameters. The authors determined the proliferation index on a large panel of human primary breast tumors by measuring the levels of incorporation of bromodeoxyuridine (BrdU) by fresh tumor specimens in culture. Previous analysis showed that the percentage of cells entering the S-phase of the cell cycle strongly correlates with tumor grade, tumor size, and estrogen and progesterone receptor status. The capacity of tumor cells to proliferate might be associated with specific genetic mutations in primary tumors. To test this hypothesis, a panel of 96 human breast carcinomas, for which the BrdU labeling index (LI) was known, were tested for loss of heterozygosity (LOH) or increased copy number (ICN) at chromosomes 1q, 3p, 13q, 17p, and 18q. On chromosome 17p, LOH and ICN were observed in 27% and 12%, respectively, of the informative breast tumors. The LOH on chromosome 17p was significantly associated with tumors having an elevated BrdU proliferation index (P = 0.022). No association (P = 0.45) was observed between BrdU LI and tumor size (T2 + T3 compared with T1), tumor grade, and lymph node status. Increased copy number on chromosome 17p, LOH or ICN on 1q, and LOH on 13q14, 18q, and 3p also showed no significant correlation with cell kinetic parameters. These data are consistent with the presence of a gene or genes on chromosome 17p13 near the YNZ22.1 locus whose normal functioning is necessary for controlling breast tumor cells proliferation in vivo.

HLA class II gene frequencies in Italy.

The frequency of HLA alleles at HLA-DR and DQ loci, and that of the related HLA-D specificities, were estimated in the Italian population. 109 healthy unrelated subjects, born in several Italian regions and living in the district of Torino, were studied. DNA typing was achieved by the restriction fragment length polymorphism (RFLP) analysis of HLA-DR beta, DQ alpha and beta genes, hybridizing specific probes with TaqI digested DNAs. The present study allowed to define in more detail the HLA class II polymorphisms in the Italian population.

HLA in juvenile dermatitis herpetiformis: clinical heterogeneity correlated with DNA and serological polymorphism.

A group of 30 Italian children affected by Dermatitis Herpetiformis (DH) was analysed for HLA region polymorphisms with both serological and DNA methods. Serological typing was performed on HLA-A, B, C, DR, DQ antigens and C4A, C4B, Bf polymorphisms. DNA RFLPs obtained with TaqI enzyme were investigated with cDNA probes specific for DR beta, DQ alpha and DQ beta genes. The results were correlated with intestinal involvement and age at onset of the disease. The following observations were made: (1) the intestinal biopsies revealed a direct correlation between degree of lesions and age at onset of DH; (2) a significantly increased relative risk (RR) was found for the following HLA antigens: A1 (RR = 2.2), B8 (RR = 6.2), Cw7 (RR = 3.9), C4AQ0 (RR = 7.4), DR3 (RR = 5.2), DR7 (RR = 4.4), DRw53 (RR = 4.7), DQw2 (RR = 6.0); (3) B8 and DR3 were significantly more frequent in patients with severe intestinal lesions; and (4) of the two DR3 subtypes revealed by RFLP typing, only 3.1 showed an increased frequency in DH patients (RR = 8.4). It is suggested that the susceptibility to Juvenile DH is determined by the same genes, within the HLA region, that are associated with Coeliac Disease.

Familial IgM mesangial nephropathy: a morphologic and immunogenetic study of three pedigrees.

Eight patients belonging to 3 unrelated families had biopsy-proven IgM mesangial nephropathy. In the first family, the mother and the 2 daughters were affected; in the second, the mother and the son; in the third, 2 sisters and the brother. Two additional sisters of the third family showed a clinical picture consistent with chronic glomerulonephritis. The clinical picture was that of hematuria and/or proteinuria. No patients had nephrotic syndrome. Genealogic investigation enabled us to discover 2 additional affected members in the kindred of the first family (1 with IgA nephropathy, 1 with clinical glomerulonephritis) and 3 other affected members in the pedigree of the third family (1 with IgA nephropathy, 1 with sclerosing glomerulonephritis, 1 with clinical glomerulonephritis). Immunogenetic studies showed the recurrence of an extended haplotype bearing DR beta 11-DQ beta 3B-DQ alpha 2-C4A3-C4B1-BfS in 9 of 10 affected members. Our data suggest that genetic factors may be involved in the mechanism of the disease and support the hypothesis that IgM nephropathy is a distinct disease entity.