Effects of nickel content on the microstructure, microhardness and corrosion behavior of high-entropy AlCoCrFeNix alloys.

In this study the effect of three different nickel concentration on the microstructure, hardness and corrosion properties of high entropy alloys (HEAs) from AlCrFeCoNi system as an alternative material for medical instruments fabrication was investigated. The analyzed HEAs were AlCrFeCoNix obtained by vacuum arc remelting from high purity raw materials and having nickel atomic ratio x = 1.0, 1.4 and 1.8. The microscopy examination revealed the dendritic morphology for the reference alloy (AlCrFeCoNi) and that the extent of the interdendritic areas increased with the concentration of nickel while Cr was more segregated in the interdendritic areas than in dendrites. Hardness values decreased as the percentage of nickel increased due to the dissolution of the precipitates in a nickel-rich matrix and consequently the formation of continuous solid solutions. The corrosion properties of the synthesized HEAs were evaluated using a potentiodynamic polarization method. The alloys were immersed in Simulated Body Fluid during one week and the corrosion parameters were recorded. The low corrosion rates, low corrosion currents and high polarization resistance attest the good stability of these HEAs in simulated biological environment indicating their possible use for surgical and dental instruments.

A lab-on-chip cell-based biosensor for label-free sensing of water toxicants.

This paper presents a lab-on-chip biosensor containing an enclosed fluidic cell culturing well seeded with live cells for rapid screening of toxicants in drinking water. The sensor is based on the innovative placement of the working electrode for the electrical cell-substrate impedance sensing (ECIS) technique as the top electrode of a quartz crystal microbalance (QCM) resonator. Cell damage induced by toxic water will cause a decrease in impedance, as well as an increase in the resonant frequency. For water toxicity tests, the biosensor's unique capabilities of performing two complementary measurements simultaneously (impedance and mass-sensing) will increase the accuracy of detection while decreasing the false-positive rate. Bovine aortic endothelial cells (BAECs) were used as toxicity sensing cells. The effects of the toxicants, ammonia, nicotine and aldicarb, on cells were monitored with both the QCM and the ECIS technique. The lab-on-chip was demonstrated to be sensitive to low concentrations of toxicants. The responses of BAECs to toxic samples occurred during the initial 5 to 20 minutes depending on the type of chemical and concentrations. Testing the multiparameter biosensor with aldicarb also demonstrated the hypothesis that using two different sensors to monitor the same cell monolayer provides cross validation and increases the accuracy of detection. For low concentrations of aldicarb, the variations in impedance measurements are insignificant in comparison with the shifts of resonant frequency monitored using the QCM resonator. A highly linear correlation between signal shifts and chemical concentrations was demonstrated for each toxicant.

De novo isochromosome 18p in two patients: cytogenetic diagnosis and confirmation by chromosome painting.

This report concerns two patients with clinical features typical for tetrasomy 18p syndrome. Chromosomal analysis revealed a male karyotype in both cases, with an additional small metacentric marker chromosome, putatively an i(18p). Fluorescent in situ hybridization with a chromosome 18-specific paint confirmed that the marker chromosome consisted of chromosome 18 material in both cases.

A retrospective CISS hybridization analysis of a case with de novo translocation t(18;22) resulting in an 18p- syndrome.

An unbalanced de novo translocation t(18;22) leading to a severely malformed liveborn girl with 18p- syndrome is described. Using the chromosomal in situ suppression (CISS) hybridization technique on 4-year-old G-banded chromosome preparations, it could be demonstrated that the translocation chromosome is composed of the long arm including the centromere of a chromosome 22 and the long arm of a chromosome 18. Consequently, the patient described here has lost the short arm including the centromere of chromosome 18. The possibility of restudying cytogenetically unsolved cases in clinical cytogenetics using older G-banded chromosome preparations with the fluorescence in situ hybridization techniques is pointed out.

A putative gene family in 15q11-13 and 16p11.2: possible implications for Prader-Willi and Angelman syndromes.

The genetic defects in Prader-Willi syndrome (PWS) and Angelman syndrome (AS) map to 15q11-13. Using microdissection, we have recently isolated several DNA probes for the critical region. Here we report that microclone MN7 detects multiple loci in 15q11-13 and 16p11.2. Eight yeast artificial chromosome (YAC) clones, two genomic phage clones, and two placenta cDNA clones were isolated to analyze these loci in detail. Two of the YAC clones map to 16p. Six YAC clones and two genomic phage clones contain a total of four or five different MN7 copies, which are spread over a large distance within 15q11-13. One cDNA clone is from chromosome 15 and one is from chromosome 16. The chromosome 15 cDNA detects transcripts of 14 and 8 kilobases in various human tissues. The presence of multiple copies of the MN7 gene family in proximal 15q may conceivably be related to the instability of this region and thus to the etiology of associated disorders.

Homozygous condition for a BrdU-requiring fragile site on chromosome 12.

A rare BrdU-sensitive fragile site, designated FRA12C*RQ24.2 has a relatively high frequency in the normal population. It can be demonstrated in a heterozygous and homozygous condition. There is no evidence that a phenotypic abnormality is associated with the expression of this site. A comparison with the fragile site FRA10B*RQ25.2 has revealed common features with FRA12C*RQ24.2.

Familial ring (20) chromosomal mosaicism.

Ring (20) chromosomal mosaicism defined by two cell lines (one normal and the other with the ring) has been demonstrated in lymphocyte and fibroblast cultures from three members of a family through two generations. Two carriers of the ring chromosome were affected and showed the typical signs of r(20) syndrome including mental retardation, microcephaly, behavioral disorders, and epilepsy. The epilepsy is characterized by complex partial seizures sometimes evolving secondarily into generalized tonic-clonic seizures and is poorly controlled by or resistant to medical treatment. The mother of the two patients, also a carrier of ring (20) chromosomal mosaicism, was clinically and phenotypically normal and did not exhibit any signs of epilepsy. Lymphocyte and fibroblast cultures from the most severely affected sib, the proband, contained the highest percentage of cells with ring (20) chromosome and revealed the greatest instability of the ring. Though it is assumed that the ring (20) chromosome arose from terminal breakage and reunion in both arms, no loss of genetic material could be documented cytogenetically. Yet the question arises of how ring chromosomal mosaicism can be passed on. One explanation might be that a chromosome 20 predisposed to terminal lesions or breaks is transmitted from the mother to her offspring. Inherited instability of this type might lead to de novo formation of the ring.

A BrdU-requiring fragile site on chromosome 12.

A BrdU-requiring fragile site, fra(12)(q24.2), on human chromosome 12 of some individuals is reported. This fragile site is inherited in a Mendelian codominant fashion and does not seem to be associated with any physical or mental abnormality in carriers. It was mostly observed as a chromatid gap: no acentric fragments, triradials or deleted chromosomes were found. The fra(12)(q24.2) was expressed in 34%-48% of metaphases in lymphocyte cultures from carriers when BrdU and FdU were added 6.5 h before harvest, while the expression ranged between 5% and 20% when the cultures were treated with BrdU alone. The fra(12)(q24.2) represents the second BrdU-requiring rare fragile site described on human chromosomes.

Trisomy 22 in a newborn with multiple malformations.

A case of complete trisomy 22 in a live-born female child with multiple malformations is reported. The karyotype of the index patient had 46 chromosomes, with one chromosome 22 missing and one supranumerary metacentric chromosome. Different banding methods and in situ hybridization revealed that the extra chromosome consists of the long arms and a part of the short arms of two chromosomes 22. Our report supplies further proof that a fetus with complete trisomy 22 can occasionally survive to term, but the condition is not compatible with life over a long period.

Familial pericentric inversion of chromosome 12.

A pericentric inversion in one of the chromosomes 12, found in two families living in the same region, is described. This inversion was detected during routine chromosomal analysis in two separate laboratories. The breakpoints were at 12p112 and 12q13. The inverted segment represented approximately 20% of the length of chromosome 12. Twenty nine descendants of carriers of the inversion were investigated, and the inversion was present in 23 of them. The other six descendants showed a normal karyotype. After correction for sample bias with the single selection scheme, a segregation ratio of 3:1 was estimated, indicating that the inverted chromosome 12 was preferentially transmitted. All the carriers of the inversion were phenotypically normal, without noticeable fertility disturbances.

On the development of a standard two-dimensional polypeptide map of the human X chromosome.

Two-dimensional gel electrophoresis analysis of a rodent-human somatic cell hybrid containing the X as the only human chromosome reveals three polypeptides that are absent in the parental cell line. The presence of these spots in human female fibroblasts indicates their human origin. The polypeptides have molecular weights and isoelectric points of 30,000/5.8,37,000/5.4, and 57,000/4.7 and are designated as PFHG 1, PFHG 2, and PFHG 3. Comparison of their molecular characteristics with those of polypeptides assigned to the human X in two other investigations shows that some but not all polypeptides are similar. Factors are discussed that might interfere with the rapid development of a standardized polypeptide map of the human X.

Exclusion of the C3 gene from the 19q133 to 19qter region by Southern analysis of human-rodent somatic cell hybrids, employing a cloned genomic C3 gene fragment.

By Southern analysis of human-rodent-somatic cell hybrids, the C3 gene could be excluded from the distal portion of the long arm of chromosome 19. In this study, a cloned genomic DNA fragment of the human C3 gene was employed as hybridisation probe. Since C3 is linked with the myotonic dystrophy (DM) and the Lewis (Le) locus, this exclusion may be relevant too for the regional assignment of these and other genes of the large chromosome 19 linkage group.