Tungsten accumulates in the intervertebral disc and vertebrae stimulating disc degeneration and upregulating markers of inflammation and pain.

Tungsten is incorporated in many industrial goods, military applications and medical devices due to its ability to impart flexibility, strength and conductance to materials. Emerging evidence has questioned the safety of tungsten exposure as studies have demonstrated it can promote tumour formation, induce pulmonary disease and alter immune function. Although tungsten is excreted from the body it can accumulate in certain organs such as the brain, colon, liver, kidneys, spleen and bones, where most of the bioaccumulation occurs. Whether prolonged tungsten exposure leads to accumulation in other tissues is unknown. The present study demonstrated that mice exposed to 15 ppm sodium tungstate for 4 weeks in their drinking water showed comparable accumulation in both the bony vertebrae and intervertebral discs (IVDs). Lumbar IVD height was significantly reduced in tungsten-exposed mice and accompanied by decreased proteoglycan content and increased fibrosis. In addition to catabolic enzymes, tungsten also increased the expression of the inflammatory cytokines IL-1ß and tumour necrosis factor (TNF)-α as well as the neurotrophic factors nerve growth factor (NGF) and brain-derived nerve factor (BDNF) in IVD cells. Tungsten significantly increased the presence of nociceptive neurons at the endplates of IVDs as observed by the expression of calcitonin gene-related peptide (CGRP) and anti-protein gene product 9.5 (PGP9.5) in endplate vessels. The present study provided evidence that tungsten may enhance disc degeneration and fibrosis as well as increase the expression of markers for pain. Therefore, tungsten toxicity may play a role in disc degeneration disease.

Foliated Quantum Error-Correcting Codes.

We show how to construct a large class of quantum error-correcting codes, known as Calderbank-Steane-Shor codes, from highly entangled cluster states. This becomes a primitive in a protocol that foliates a series of such cluster states into a much larger cluster state, implementing foliated quantum error correction. We exemplify this construction with several familiar quantum error-correction codes and propose a generic method for decoding foliated codes. We numerically evaluate the error-correction performance of a family of finite-rate Calderbank-Steane-Shor codes known as turbo codes, finding that they perform well over moderate depth foliations. Foliated codes have applications for quantum repeaters and fault-tolerant measurement-based quantum computation.

Variation in measurements of transtibial stump model volume: a comparison of five methods.

OBJECTIVE: To determine the right moment for fitting the first prosthesis, it is necessary to know when the volume of the stump has stabilized. The aim of this study is to analyze variation in measurements of transtibial stump model volumes using the water immersion method, the Design TT system, the Omega Tracer system, circumferential measurements, and anthropometric measurements. DESIGN: Nine stump models were measured on two occasions, each consisting of two sessions. In each session, two observers measured the model using each of the five methods. The grand mean volume for each method was calculated. Variance components and their two-way interactions were calculated of the measurement conditions. Repeatability coefficients were calculated for each method. RESULTS: The grand means of the five methods show systematic differences in volume measurements. Error variance was small (6.4%) relative to the total variance. Method and interaction between stump model and method contributed 82.6% to the error variance. Repeatability coefficients of the methods ranged from 45 ml for the Omega Tracer system to 155 ml for the anthropometric measurements. CONCLUSIONS: Error variation in measurement results can be attributed for 82.6% to measurement method and interaction between stump model and method. The Omega Tracer system had the smallest repeatability coefficient, indicating that it is the most reliable method.

Reconstitution of active telomerase in primary human foreskin fibroblasts: effects on proliferative characteristics and response to ionizing radiation.

PURPOSE: Telomere shortening has been proposed to trigger senescence, and since most primary cells do not express active telomerase, reactivation of telomerase activity was proposed as a safe and non-transforming way of immortalizing cells. However, to study radiation responses, it is as yet unclear whether cells immortalized by telomerase reactivation behave in a similar manner as their parental primary cells. MATERIALS AND METHODS: Primary human foreskin fibroblasts were transfected with the human catalytic subunit of telomerase, the reverse transcriptase (hTERT), and their growth characteristics and response to DNA damage were characterized. RESULTS: The sole expression of the human hTERT was sufficient to immortalize the human foreskin fibroblasts. With time in culture, the immortalized cells almost doubled their average telomeric length and the clonal population contained almost no post-mitotic fibroblasts anymore. Up to 300 population doublings, no alterations compared with the parental primary cells were seen in terms of clonogenic radiosensitivity, DNA double-strand break repair, radiation-induced increases in p53 and p21(WAF-1,CIP-1) expression, and the G1/S and G2/M cell cycle checkpoints. Moreover, mitogen-induced mitotic arrest of fibroblasts was still possible in the hTERT-immortalized clones. CONCLUSIONS: Immortalizing fibroblasts by reconstitution of active telomerase seems a good, reliable manner to generate a large source of cells with a radiation damage response similar to the primary cells.

BRCA1 and BRCA2 heterozygosity and repair of X-ray-induced DNA damage.

PURPOSE: Up to 90% of hereditary breast cancer cases are linked to germ-line mutations in one of the two copies of the BRCA1 or BRCA2 genes. Brca1 and Brca2 proteins are both involved in the cellular defence against DNA damage, although the precise function of the proteins is still not known. Some studies on a small number of samples as well as the present pilot study also suggested that BRCA1 heterozygosity may lead to impaired repair of ionizing-radiation-induced DNA double-strand breaks. The purpose of the study was to test in a larger family-matched study whether carriers of BRCA1 or BRCA2 mutations have an increased sensitivity to ionizing radiation. MATERIALS AND METHODS: In a blind study, the effect of different germ-line mutations in one allele of the BRCA1 or BRCA2 gene on the ability to repair X-ray-induced DNA breaks was investigated. Fibroblasts and lymphocytes were taken from heterozygotic individuals (BRCA1+ /- and BRCA2+ /-) with different mutations and from relatives proven to be non-carriers of the BRCA mutations. Rejoining of DNA breaks was analysed by pulsed-field gel electrophoresis (for fibroblasts) or the comet assay (for lymphocytes). RESULTS: Significant interindividual differences were found in the capacities of the fibroblasts and lymphocytes to rejoin DNA breaks induced by X-radiation. However, these differences were not related to heterozygosity in BRCA1 or BRCA2. CONCLUSIONS: Cells from carriers of mutations in one allele of the BRCA1 or BRCA2 genes have no gross defects in their ability to rejoin radiation-induced DNA breaks. Hence, these carriers may not be at risk of developing excess normal tissue reactions after radiotherapy consistent with data from recent clinical studies.

Azoxymethane induces KI-ras activation in the tumor resistant AKR/J mouse colon.

A differential susceptibility phenotype to the organotropic colon carcinogen azoxymethane (AOM) has been described in mice. The following studies were undertaken to test the hypothesis that intraspecific susceptibility can be accounted for by the specific complement of genetic alterations acquired by precancerous colon lesions referred to as aberrant crypt foci (ACF). As an initial approach to this question, mutations in codons 12 and 13 of the Ki-ras proto-oncogene were assessed in ACF, normal-appearing AOM-treated colonic epithelium, and tumors from A/J and SWR/J (susceptible) as well as AKR/J (resistant) mice. Four-week-old male mice were injected intraperitonealy, with AOM once a week for a total of 6 wk and killed 4 and 24 wk after the last injection. DNA was isolated from microdissected tissue, and polymerase chain reaction (PCR)-amplified products of Ki-ras exon 1 (codons 12 and 13) were directly sequenced from microdissected tissues. At 4 wk after AOM exposure, there was no significant difference in the frequency of Ki-ras activation (20-33%) between the three strains. Ki-ras mRNA expression was also evaluated by reverse transcription (RT)-PCR analysis and was comparably reduced (40-50%) in all three strains at the 4 wk time point. However, Ki-ras expression returned to normal by 24 wk after treatment. Finally, to gain further insight into the molecular pathogenesis underlying this experimental tumor model, analysis of the adenomatous polyposis coli (APC) protein within the colonic epithelium was undertaken by using an immunohistochemical approach. Although the APC protein was lost to a varying extent in tumors from A/J and SWR/J mice, the full-length form of the protein was still present in precancerous ACF isolated from each of the three strains, regardless of the degree of dysplasia of the lesion. A further molecular genetic analyses of ACF will be required to gain a more complete understanding of the molecular basis of tumor susceptibility phenotype in this murine model.

Expression analysis of the group IIA secretory phospholipase A(2) in mice with differential susceptibility to azoxymethane-induced colon tumorigenesis.

The murine non-pancreatic secretory phospholipase A(2) (sPLA(2)) has been proposed as a tumor modifier of multiple intestinal neoplasia (Min). A genetic polymorphism in the mouse gene that causes a disruption in exon 3 results in loss of functional protein. Mouse strains with a disrupted sPLA(2) gene are susceptible to the Min phenotype and develop numerous intestinal polyps, whereas mice with normal sPLA(2) develop only a limited number of polyps. The following study was undertaken to test the hypothesis that sPLA(2) plays an equivalent role in murine susceptibility to the colon carcinogen azoxymethane (AOM). sPLA(2) status was confirmed by sequencing in mice that are highly susceptible (A/J), susceptible (SWR/J) and resistant (AKR/J) to AOM-induced tumorigenesis. Constitutive expression of sPLA(2) mRNA was compared in small intestine and colon of untreated mice using semi-quantitative RT-PCR. Whereas mRNA expression was nearly absent in A/J mice, AKR/J mice exhibited extensive expression throughout the intestine. Despite the wild-type sPLA(2) gene, colonic mRNA expression in SWR/J mice was significantly lower relative to AKR/J. Immunohistochemical analysis of sPLA(2) protein confirmed the mRNA data. The effect of AOM on colonic sPLA(2) expression was also examined. Twenty-four weeks after the last of six weekly injections of AOM (10 mg/kg i.p.), RT-PCR analysis of distal colons revealed a significant increase in mRNA in normal-appearing epithelium and tumor tissue from AOM-treated mice relative to controls. However, there was no corresponding increase in protein expression in A/J mice. The absence of sPLA(2) expression within control colons of tumor-susceptible A/J mice together with low expression in SWR/J colons is consistent with its potential role as an intestinal tumor modifier, but the carcinogen-induced increase in expression raises doubts as to the significance of sPLA(2) in inhibiting carcinogenesis.

Preliminary analysis of azoxymethane-induced colon tumorigenesis in mouse aggregation chimeras.

Inbred mice exhibit differential susceptibility to colon carcinogens. The following study addresses the possibility that differences are intrinsic to colonic mucosa (cell autonomous) or are mediated by extracolonic systemic factors (e.g. liver activation of carcinogens). Our approach was to construct mouse aggregation chimeras, mice whose tissues are a mosaic of cells derived from two parental genotypes, from a susceptible (SWR) and a resistant (DBA/2) strain. Forty-five embryo aggregations yielded 11 viable pups, four of which were chimeric by coat color. Six-week-old SWR<-->BA/2 chimeras were injected i.p. with azoxymethane (AOM) once a week for 8 weeks (5 and 7.5 mg/kg body wt for 2 weeks followed by 10 mg/kg for 6 weeks) and tumor incidence in distal colon was evaluated 15 weeks after the last injection. Additional groups of parental mice received the same treatment. In the parental SWR treatment group, 1.7 +/- 0.82 tumors/colon were found. No tumors were observed in AOM-treated DBA/2 mice. In SWR<-->DBA/2 chimeras exposed to AOM, 2.8 +/- 2.1 tumors/colon were found. Tumor lineage was examined in paraffin sections stained with Dolichos biflorus agglutinin-peroxidase, a cell surface specific marker that stains intestinal endothelial cells of SWR and epithelial cells of DBA/2. Cellular lineage of tumors was further evaluated by microsatellite analysis of DNA isolated by microdissection. There was no significant difference in tumor incidence between SWR parental and chimera treatment groups. Histochemical analysis of tumor tissue in chimeras suggested that most tumors were derived from SWR. However, subsequent genetic analysis of tumors indicated mixed parental composition. These preliminary studies suggest that DBA/2 resistance mechanisms are not sufficient to protect adjacent SWR-derived epithelium from the tumorigenic effects of AOM.

1-(2-Thienyl)-2-phenylethylamines as potential non-stimulant anorectics.

A series of 1-(2-thienyl)-2-phenylethylamines was synthesized and tested for anorectic and motor activity effects in rats. Phenyl ring substituents included Cl, Br, F, CF3, CH3, OCH3, and NO2; amino group substituents included alkyl, benzyl and acetyl groups. About half of the compounds produced significant anorexia; only one of these active anorectics increased motor activity. The three most potent non-stimulant anorectics were: 1-(2-thienyl)-2-(4-chlorophenyl)ethylamine, its N-isopropyl analogue, and N-isopropyl-1-(2-thienyl)-2-(4-fluorophenyl)ethylamine.

Anorectic and motor activity effects of some 1-benzylcycloalkylamines in the rat.

1. A series of 1-benzylcycloalkylamines with cycloalkyl rings of five, six or seven carbons and with various benzyl ring substituents (3-Cl, 4-Cl, 4-F, 3-CF3) was prepared and tested for anorectic and motor activity effects in rats. 2. Two potent, non-stimulant, anorectics were found: 1-(3-chlorobenzyl)-cycloheptylamine, and its N-methyl analogue. The activity of these compounds resembled that of chlorphentermine.

A novel activity cage for rats: characterization of some phenylethylamine derivatives with central stimulant and depressant effects.

1. A novel activity cage for rats is described. Eight light beams are aimed at a light-conducting perspex rod at the centre of a cylindrical cage. The photoresistor at the end of the rod detects the changes in light intensity produced by interruption of the light beams. 2. The apparatus is simple to operate and was capable of detecting small differences in the motor activity of groups of rats. 3. Dose-dependent increases in motor activity were produced by dexamphetamine (1.36 to 27.3 mumol/kg, i.p.). The depressant effects produced by 20 mumol/kg doses of nonfenfluramine were greater than those of fenfluramine. Large doses (100 mumol/kg) of tranylcypromine stimulated motor activity whereas its cis-isomer, cis-2-phenylcyclopropylamine, depressed motor activity.

Comparison of the anorectic and motor activity effects of some aminoindanes, 2-aminotetralin and amphetamine in the rat.

1. The anorectic and motor activity effects of 1-aminoindane, 2-aminoindane, some N-substituted 2-aminoindanes, 2-aminotetralin, amphetamine and fenfluramine were determined in rats. 2. The two compounds with structures most like the extended conformation of amphetamine, 2-aminotetralin and 2-aminoindane, were potent anorectics. At dosages which halved the intake of food over 1 h, amphetamine increased motor activity, 2-aminotetralin had no effect, and 2-aminoindane reduced motor activity. 3. Both the anorectic and central stimulant actions of 2-aminoindane were absent in N-ethyl- and N-isopropyl-2-aminoindane. 4. 1-Aminoindane, whose structure is like the folded conformation of amphetamine, produced a small anorectic effect and depressed motor activity.

1,2-Diphenylethylamines as potential non-stimulant anorectics.

A series of 1,2-diphenylethylamines has been synthesized in which the phenyl rings were substituted with Cl, OCH3 or CF3 at various positions and in various combinations. Four N-ethylpiperazino and N-ethylmorpholino compounds were also prepared. When tested in rats, some of the compounds were found to be potent anorectics and none of them stimulated motor activity.