Molecular events including p53 and k-ras alterations in the in vitro progression of a human colorectal adenoma cell line to an adenocarcinoma

The aim of the current study was to identify genetic abnormalities in human colorectal adenoma and carcinoma derived cell lines, and to determine whether the genetic changes which occur in vitro are relevant to the in vivo situation. Loss of 1p(33-35) region was shown to be the most common chromosome 1 abnormality and loss of heterozygosity (LOH) of the DCC gene and/or adjacent sequences was detected in all adenoma derived cells as well as the carcinoma cell lines. The level of p53 protein was also investigated as increased cellular p53 protein had previously been associated with mutation of the p53 gene. A further aim was to investigate genetic changes in our in vitro model of tumour progression, where the adenoma derived PC/AA cell line has previously been converted in vitro to two distinct tumorigenic phenotypes, producing either an adenocarcinoma or a mucinous carcinoma in athymic nude mice. Progression to the adenocarcinoma phenotype was shown to involve a specific chromosome 1 rearrangement, loss of both normal copies of chromosome 18 (although DCC gene sequences were retained), loss of the remaining wild type allele of k-ras resulting in homozygosity for the k-ras codon 12 mutation and increased cellular p53 protein as detected by SDS-PAGE Western blotting. The increase in p53 protein was shown not to be due to the acquisition of a mutation in the p53 gene. Interestingly, progression of the adenoma derived PC/AA cell line to the mucinous malignant phenotype did not involve any of these molecular rearrangements, suggesting that different genetically distinct pathways are involved in colorectal carcinogenesis. These studies show that the genetic changes in our in vitro model of human colorectal tumour progression are similar to those observed in in vivo studies.     

Clinical and biochemical studies in an American child with sialuria

Sialuria is a rare inborn error of sialic acid (NeuAc) metabolism resulting from failure of CMP-NeuAc to adequately feedback inhibit the rate-limiting enzyme in sialic acid synthesis, UDP N-acetylglucosamine (UDP-GlcNAc) 2-epimerase. We describe the fourth reported sialuria patient, T.W., whose clinical features include developmental delay, coarse facies, and massive urinary excretion of sialic acid. Biochemical studies of T.W. fibroblasts revealed a 200-fold increase in free NeuAc content compared with normal. Bound NeuAc was only slightly elevated. The free NeuAc was predominantly in the cytosol fraction of fibroblasts after differential centrifugation, with only 4% of the free NeuAc content in other (nuclear, granular, and microsomal) cellular compartments. CMP-NeuAc inhibited UDP-GlcNAc 2-epimerase by 80% in normal fibroblasts but inhibited the epimerase of T.W. (sialuria) cells by only 13%. Cytidine feeding of sialuria fibroblasts decreased the intracellular free NeuAc content by 47%; this was accompanied by a fourfold increase in CMP-NeuAc, which may be sufficient to feedback inhibit the mutant epimerase and reduce free NeuAc production. Cytoplasmic pH was determined by the pH sensitive fluorescent indicator 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, pentaacetoxymethylester (BCECF/AM) using the H+ equilibration method. The intracellular pH of sialuria fibroblasts, 7.18 +/- 0.04, was not found to be significantly different from that of normal cells (7.19 +/- 0.08).     

Gamow-Teller matrix elements for two-neutrino double beta decay within a second quasi-random-phase approximation

The ascendency of the cerebral cortex in mammals naturally raises questions about the role of the archetypal subcortical centers we share in common with other phyla. Here we report a situation in which an ancient oculomotor control center, the nucleus of the optic tract, is not so much dominated by the cerebral cortex as served by it. We suggest that the organization of cortical output to subcortical centers may be helpful in understanding the function of the cerebral cortex.     

A leukocyte homologue of the IL-8 receptor CXCR-2 mediates the accumulation of macrophages in atherosclerotic lesions of LDL receptor-deficient mice

Cancer complicating pregnancy is uncommon, with an incidence of approximately 1 in 1000 pregnancies. The obstetrician attending 250 deliveries per year would need to accumulate 40 years of clinical experience to encounter two to three cases of PABC. The increases in the size, weight, vascularity, and density of the breasts associated with pregnancy make the detection of mass lesions difficult both clinically and mammographically. Most of the benign lesions seen in pregnancy are the same ones seen in the nongravid state. Most cases of PABC present as painless masses, and as many as 90% of these masses are detected by breast self-examination. Women with PABC generally have more advanced disease with larger tumors, a higher percentage of inoperable lesions, and a higher percentage of nodal involvement. Because most PABC presents with a palpable mass, the role of imaging modalities in the evaluation of these patients remains limited. Fine-needle aspiration cytology is the initial procedure of choice for evaluating breast masses during pregnancy and lactation. Therapeutic abortion does not improve survival. The general principle is to treat the cancer and to allow the pregnancy to proceed. No studies have shown an adverse effect of a subsequent pregnancy even in patients with positive axillary nodes and patients in whom pregnancy occurs earlier than 2 years after treatment.     

Scanning electron microscopic study and shear bond strength measurement with 5% and 37% phosphoric acid

Direct bonding of orthodontic attachments has become a clinical reality with the application of the acid etch technique, using 37% phosphoric acid. The objective of this study was to detect the etch pattern with scanning electron microscopy and the shear bond strength with a Hounsefield tensometer (Nene Instruments Ltd., Northampton, England) by using 37% and 5% phosphoric acid (H3PO4). It was observed that with 5% H3PO4 there was minimal enamel loss compared with 37% H3PO4. There was no significant difference in shear bond strength, when enamel surface was etched with 5% H3PO4 and 37% H3PO4.