MEMRI and tumors: a method for the evaluation of the contribution of Mn(II) ions in the extracellular compartment

The purpose of the work was to set‐up a simple method to evaluate the contribution of Mn²⁺ ions in the intra‐ and extracellular tumor compartments in a MEMRI experiment. This task has been tackled by “silencing” the relaxation enhancement arising from Mn²⁺ ions in the extracellular space. In vitro relaxometric measurements allowed assessment of the sequestering activity of DO2A (1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid) towards Mn²⁺ ions, as the addition of Ca‐DO2A to a solution of MnCl₂ causes a drop of relaxivity upon the formation of the highly stable and low‐relaxivity Mn‐DO2A. It has been proved that the sequestering ability of DO2A towards Mn²⁺ ions is also fully effective in the presence of serum albumin. Moreover, it has been shown that Mn‐DO2A does not enter cell membranes, nor does the presence of Ca‐DO2A in the extracellular space prompt migration of Mn ions from the intracellular compartment. On this basis the in vivo, instantaneous, drop in SE% (percent signal enhancement) in T₁‐weighted images is taken as evidence of the sequestration of extracellular Mn²⁺ ions upon addition of Ca‐DO2A. By applying the method to B16F10 tumor bearing mice, T₁ decrease is readily detected in the tumor region, whereas a negligible change in SE% is observed in kidneys, liver and muscle. The relaxometric MRI results have been validated by ICP‐MS measurements. Copyright © 2015 John Wiley & Sons, Ltd.     

Emergence and scattering of multiple neurofibromatosis (NF1)-related sequences during hominoid evolution suggest a process of pericentromeric interchromosomal transposition

Type 1 neurofibromatosis (NF1) gene encodes for a member of the GTPase activating protein family and is considered to be a tumor suppressor gene. Its very high rate of de novo mutation in humans led us to study a specific feature of this gene: the presence of numerous NF1-related sequences. According to our results, the human genome contains at least 11 NF1-related sequences, nine of which are scattered near centromeric sequences of seven different chromosomes. These NF1-related sequences, whose extent is quite varied according to loci, are unprocessed copies of the NF1 gene, and bear numerous mutations. A phylogenetic analysis of the six largest sequences indicates that they are all derived from a common ancestor, which would have appeared 22-33 million years ago, and was subsequently duplicated several times during hominoid evolution. The most recent duplication and interchromosomal transposition occurred in the last million years suggesting that the process could still be ongoing. Intriguing similarities between the evolution of alpha- satellite DNA and NF1-related sequences suggest the involvement of a common genetic mechanism for the generation and pericentric spreading of these NF1 partial copies.      

Psychometric properties of the SUNYA revision of the psychosomatic symptom checklist

The Psychosomatic Symptom Checklist (PSC), a questionnaire assessing psychosomatic symptoms, was administered to two separate samples of college students. For Sample 1 (N=698),the questionnaire was readministered to three separate subsets at intervals of either 1 week (N=143),4 weeks (N=74),or 8 weeks (N=48).Each subset of subjects recompleted the PSC on only one of the three retest intervals. Based on the initial administration an analysis of the normative data revealed a mean total score of 23.7, suggesting a relatively low degree of psychosomatic symptoms in this group. Although total scores decreased slightly over time, test-retest correlations remained high (r>0.80, P<0.0001).Individual item correlations varied and also decreased across time; however, the majority of correlations was greater than r=0.50 throughout. Sample 2 (N=249)completed the PSC, Beck Depression Inventory (BDI), State-Trait Anxiety Inventory (STAI-X), and Rathus Assertiveness Scale (RAS), and intercorrelations were computed between these measures. This analysis revealed little overlap between the psychosomatic complaints assessed by the PSC and other commonly used measures of psychological distress. Finally, a factor analysis revealed one major factor on which all but 2 of the 17 questionnaire items loaded significantly. These results suggest that the PSC is sensitive to psychosomatic distress and remains reliable over time.This reaserch was supported in part by Grants NS-15235 and NS-16891 from NINCDS.     

Chromosomal assignment of human O6-methylguanine-DNA-methyltransferase gene by hamster-human somatic cell hybrids.

Using an in vitro assay to measure O6-methylguanine-DNA-methyltransferase (MT) activity in cell extracts from a panel of human-hamster cell hybrids, we were able to locate the human MT gene on chromosome 10. Chinese hamster cells have little or no MT activity and the presence of human chromosome 10 was a necessary condition for MT activity in cell hybrids. In some cell hybrids carrying chromosome 10, however, MT activity was not higher than that of hamster cells. As an explanation for this result, genetic determinants repressing MT expression and/or activity might be present in other human chromosomes carried by MT-negative cell hybrids. Partial hyperploidy of the hamster karyotype, variable activity of the parental human cell lines and changes during subculturing of the cell hybrids might also account for the lack of enzymatic activity in chromosome 10 containing hybrids.     

Homozygosity mapping of achromatopsia to chromosome 2 using DNA pooling

Achromatopsia is an autosomal recessive disease of the retina, characterized clinically by an inability to distinguish colors, impaired visual acuity, nystagmus and photophobia. A genome-wide search for linkage was performed using an inbred Jewish kindred from Iran. To facilitate the genome-wide search, we utilized a DNA pooling strategy which takes advantage of the likelihood that the disease in this inbred kindred is inherited by all affected individuals from a common founder. Equal molar amounts of DNA from all affected individuals were pooled and used as the PCR template for short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected members of the kindred was used as a control. A reduction in the number of alleles in the affected versus control pool was observed at several loci. Upon genotyping of individual family members, significant linkage was established between the disease phenotype and markers localized on chromosome 2. The highest LOD score observed was 5.4 (theta = 0). When four additional small unrelated families were genotyped, the combined peak LOD score was 8.2. Analysis of recombinant chromosomes revealed that the disease gene lies within a 30 cM interval which spans the centromere. Additional fine-mapping studies identified a region of homozygosity in all affected individuals, narrowing the region to 14 cM. A candidate gene for achromatopsia was excluded from this disease interval by radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an essential first step in the identification of the disease-causing gene.      

Immunocytochemical detection of lactoferrin in human gastric carcinomas and adenomas

In gastric carcinomas, including 20 cases of intestinal type and 10 cases of diffuse type, in adenomas with mild to severe dysplasia (20 cases), and in hyperplastic polyps (10 cases), the presence of lactoferrin was investigated by immunohistochemistry. Incomplete or complete intestinal metaplasia or both and normal gastric mucosa were also tested. Preoperative hematocrit and serum iron levels (18 patients) were recorded. An evident reactivity for lactoferrin was encountered in intestinal type carcinomas, adenomas, and incomplete intestinal metaplasia, whereas diffuse-type carcinomas, hyperplastic polyps, and complete intestinal metaplasia were always unstained; mucous neck cells of the antrum and body were also positive for lactoferrin. The results are discussed in relation to the increased requirement of iron by neoplastic cells, although in gastric carcinomas serum iron levels appear to be unrelated to the immunohistochemical presence of lactoferrin.