Establishing the Maximum Collectivity in Highly Deformed N=Z Nuclei.

The lifetimes of the first excited 2^{+} states in the N=Z nuclei ^{80}Zr, ^{78}Y, and ^{76}Sr have been measured using the γ-ray line shape method following population via nucleon-knockout reactions from intermediate-energy rare-isotope beams. The extracted reduced electromagnetic transition strengths yield new information on where the collectivity is maximized and provide evidence for a significant, and as yet unexplained, odd-odd vs even-even staggering in the observed values. The experimental results are analyzed in the context of state-of-the-art nuclear density-functional model calculations.

Lifetime Measurements and Triple Coexisting Band Structure in

Lifetime measurements of excited states in the neutron-rich nucleus ^{43}S were performed by applying the recoil-distance method on fast rare-isotope beams in conjunction with the Gamma-Ray Energy Tracking In-beam Nuclear Array. The new data based on γγ coincidences and lifetime measurements resolve a doublet of (3/2^{-}) and (5/2^{-}) states at low excitation energies. Results were compared to the π(sd)-ν(pf) shell model and antisymmetrized molecular dynamics calculations. The consistency with the theoretical calculations identifies a possible appearance of three coexisting bands near the ground state of ^{43}S: the K^{π}=1/2^{-} band built on a prolate-deformed ground state, a band built on an isomer with a 1f_{7/2}^{-1} character, and a suggested excited band built on a newly discovered doublet state. The latter further confirms the collapse of the N=28 shell closure in the neutron-rich region.

Enhanced Electric Dipole Strength for the Weakly Bound States in

An enhanced low-energy electric dipole (E1) strength is identified for the weakly bound excited states of the neutron-rich isotope ^{27}Ne. The Doppler-shift lifetime measurements employing a combination of the γ-ray tracking array GRETINA, the plunger device, and the S800 spectrograph determine the lower limit of 0.030 e^{2} fm^{2} or 0.052 W.u. for the 1/2^{+}→3/2^{-} E1 transition in ^{27}Ne, representing one of the strongest E1 strengths observed among the bound discrete states in this mass region. This value is at least 30 times larger than that measured for the 3/2^{-} decay to the 3/2_{gs}^{+} ground state. A comparison of the present results to large-scale shell-model calculations points to an important role of core excitations and deformation in the observed E1 enhancement, suggesting a novel example of the electric dipole modes manifested in weakly bound deformed systems.

Giardia outbreak associated with a roadside spring in Rensselaer County, New York.

In September 2009, the Rensselaer County Department of Health investigated an increase in Giardia duodenalis cases. The epidemiological investigation identified that a source of the illness could be a roadside spring located in the eastern part of the county. Epidemiological and environmental health staff conducted a site visit to the roadside spring and found several concerns. Water samples were collected from the roadside spring and sent to the New York State Department of Health for analysis. The water sample results indicated the presence of empty Giardia cysts. Prevention methods occurred and the roadside spring was destroyed. A total of 36 laboratory-confirmed cases of Giardia were identified from this outbreak that included residents of New York State and Massachusetts.

Nanofabrication for transistor matrix produced by self-aligned imprint lithography.

This paper describes an approach of combining nanofabrication techniques with roll-to-roll fabrication of thin film transistor backplanes for flexible display applications.

Intestinal uptake and metabolism of auranofin, a new oral gold-based antiarthritis drug.

Auranofin, 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranosato-S-(triethy lphosphine)- gold(I), an experimental antiarthritis pharmaceutical, metabolized in contact with hamster or rat gut wall to yield the deacetylated form of the drug. This product, 1-thio-beta-D-glucopyranosato-S-(triethylphosphine)gold(I), passed through hamster or rat intestinal wall in an everted gut experiment. The metabolite was separated by high-performance liquid chromatography and characterized by retention time, chemical reactivity to yield a known product, and comparison to a synthetic sample of the metabolite.

Heart imaging with cationic complexes of technetium.

The cationic technetium-99 complex trans-[99TC(dmpe)2Cl2]+, where dmpe is bis(1,2-dimethylphosphino)ethane or (CH3)2P-CH2-P(CH3)2, has been prepared and characterized by single-crystal, x-ray structural analysis. The technetium-99m analog, trans-(99mTc(dmpe) 2Cl2]+, has also been prepared and shown to yield excellent gamma-ray images of the heart. The purposeful design, characterization, and synthesis of this technetium-99m radiopharmaceutical represents a striking application of fundamental inorganic chemistry to a problem in applied nuclear medicine.

Schedule-induced polydipsia in lines of rats selectively bred for high and low ethanol preference.

Ethanol drinking was assessed in the P/NP, HAD1/LAD1, and HAD2/LAD2 lines of rats under environmental conditions that produce schedule-induced polydipsia. Female rats (n = 8/line), maintained at 85% of free-feeding body weights, underwent daily 1-h sessions during which 45-mg food pellets were delivered every 60 s. Water, 2, 4, 8, 16, or 32% w/v ethanol solution was available from a single bottle for 8 consecutive sessions at each concentration, with blood-ethanol levels (BELs) determined after selected sessions. P and HAD2 rats drank more water and ethanol than their non-preferring counterparts, while HAD1 and LAD1 rats did not differ. Ethanol intake and BELs were positively correlated (r = 0.75) across lines. Finally, rats were allowed 14 daily choice sessions with 8% ethanol and water concurrently available. Water intake generally exceeded ethanol intake in all lines, while P rats drank similar amounts of both fluids. These line differences indicate pleiotropic effects of genes that mediate ethanol intake and schedule-induced behaviors.

A DNA polymerase mutation that suppresses the segregation bias of an ARS plasmid in Saccharomyces cerevisiae.

Yeast autonomously replicating sequence (ARS) plasmids exhibit an unusual segregation pattern during mitosis. While the nucleus divides equally into mother and daughter cells, all copies of the ARS plasmid will often remain in the mother cell. A screen was designed to isolate mutations that suppress this segregation bias. A plasmid with a weak ARS (wARS) that displayed an extremely high segregation bias was constructed. When cells were grown under selection for the wARS plasmid, the resulting colonies grew slowly and had abnormal morphology. A spontaneous recessive mutation that restored normal colony morphology was identified. This mutation suppressed plasmid segregation bias, as indicated by the increased stability of the wARS plasmid in the mutant cells even though the plasmid was present at a lower copy number. An ARS1 plasmid was also more stable in mutant cells than in wild-type cells. The wild-type allele for this mutant gene was cloned and identified as POL delta (CDC2). This gene encodes DNA polymerase delta, which is essential for DNA replication. These results indicate that DNA polymerase delta plays some role in causing the segregation bias of ARS plasmids.

Some of the signals for 3'-end formation in transcription of the Saccharomyces cerevisiae Ty-D15 element are immediately downstream of the initiation site.

Fragments from the Ty-D15 element of Saccharomyces cerevisiae were assayed for the ability to direct 3'-end formation for RNA initiated by the GAL1 promoter. The delta, the direct repeat at each end of the element, was capable of forming 3' ends at two sites, an inefficient upstream site and an efficient downstream site near the end of the delta. Different sequences were required for 3'-end formation at these sites. For the efficient site, all transcripts had 3' ends in the delta and no downstream transcription was detected, which suggested that these sequences terminate transcription. Surprisingly, the delta region downstream of the initiation site for Ty RNA comprised part of this major site and terminated more than 50% of the transcripts that read into it. Sequences necessary for the efficient site were localized to two small regions. Both regions were upstream of the 3' end and contained similarities to a tripartite consensus sequence that has been proposed as a terminator element. Sequences near the position of the 3' end could also affect termination; a short G + C-rich sequence inserted just downstream changed an efficient terminator to an inefficient one. Initiation in the delta had no effect on the efficiency or positions or termination in that delta. A new initiation site was seen when the same delta terminated transcription, but transcriptional interference did not occur, since the amount of initiation was not decreased.

A region internal to the coding sequences is essential for transcription of the yeast Ty-D15 element.

The major transcript of the yeast transposable element Ty1 has its 5' end in one delta and the 3' end in the opposite delta, the direct repeats of about 335 base pairs (bp) at each end of the element. The transcriptional initiation signals of the Ty-D15 element that give rise to this transcript were found to have a number of unusual characteristics. The 5' delta by itself, which contained the initiation site for Ty transcription, gave no detectable transcription. A region internal to the transcript in a translated part of the element and about 140 bp downstream of the 5' delta was essential for initiation of the major Ty transcript. This internal activating region (IAR) had several interesting properties. When the portion of the delta upstream of the initiation site was replaced with DNA fragments that did not by themselves act as promoters, initiation directed by the IAR still occurred at about the same position, 200 to 400 bp upstream of the IAR. If fragments containing the IAR were inverted, transcription could still occur. When 468 or 636 bp was inserted between the delta and the IAR, initiations occurred near the normal delta initiation site and in the inserted DNA. Therefore, the location and properties of transcription signals for Ty-D15 differ considerably from those expected for a yeast gene transcribed by RNA polymerase II.

Complementary transcripts from two genes necessary for normal meiosis in the yeast Saccharomyces cerevisiae.

The SPO12 gene, which is required for meiosis I chromosome division during sporulation of the yeast Saccharomyces cerevisiae, has been isolated. DNA sequencing has identified an open reading frame of 173 codons that encodes the putative SPO12 protein and has no significant sequence similarities to known genes. The last 15 amino acids of this putative protein have a high negative charge, which appears to be required for function. A second sporulation-specific gene, designated SPO16, was found adjacent to SPO12 and shown to be necessary for efficient spore formation. The two genes are encoded on opposite DNA strands with only 103 nucleotides between the termination codons. Up to 700 nucleotides of the SPO12 and SPO16 transcripts are complementary, and the 3' untranslated region of the longest SPO16 transcript is complementary to all or nearly all of the SPO12 mRNA. A strain homozygous for an insertion which removes the complementarity between the SPO12 and SPO16 mRNAs has an efficiency of sporulation, number of spores per ascus, and spore viability identical to those of a wild-type strain. The complementarity therefore has either no function or only a subtle function in meiosis and sporulation.

Developmental regulation of SPO13, a gene required for separation of homologous chromosomes at meiosis I.

Previous studies have demonstrated that the SPO13 gene is required for chromosome separation during meiosis I in Saccharomyces cerevisiae. In the presence of the spo13-1 nonsense mutation, MATa/MAT alpha diploid cells complete a number of events typical of meiosis I including premeiotic DNA synthesis, genetic recombination, and spindle formation. Disjunction of homologous chromosomes, however, fails to occur. Instead, cells proceed through a single meiosis II-like division and form two diploid spores. In this paper, we report the cloning of this essential meiotic gene and an analysis of its transcription during vegetative growth and sporulation. Disruptions of SPO13 in haploid and diploid cells show that it is dispensible for mitotic cell division. Diploids homozygous for the disruptions behave similarly to spo13-1 mutants; they sporulate at wild-type levels and produce two-spored asci. The DNA region complementing spo13-1 encodes two overlapping transcripts, which have the same 3' end but different 5' ends. The major transcript is 400 bases shorter than the larger, less abundant one. The shorter RNA is sufficient to complement the spo13-1 mutation. While both transcripts are undetectable or just barely detectable in vegetative cultures, they each undergo a greater than 70-fold induction early during sporulation, reaching a maximum level about the time of the first meiotic division. In synchronously sporulating populations, the transcripts nearly disappear before the completion of ascus formation. Nonsporulating cells homozygous for the mating-type locus show a small increase in abundance (less than 5% of the increase in sporulating cells) of both transcripts in sporulation medium. These results indicate that expression of the SPO13 gene is developmentally regulated and starvation alone, independent of the genotype at MAT, can trigger initial induction.

Increased susceptibility to streptozotocin-induced beta-cell apoptosis and delayed autoimmune diabetes in alkylpurine-DNA-N-glycosylase-deficient mice.

Type 1 diabetes is thought to occur as a result of the loss of insulin-producing pancreatic beta cells by an environmentally triggered autoimmune reaction. In rodent models of diabetes, streptozotocin (STZ), a genotoxic methylating agent that is targeted to the beta cells, is used to trigger the initial cell death. High single doses of STZ cause extensive beta-cell necrosis, while multiple low doses induce limited apoptosis, which elicits an autoimmune reaction that eliminates the remaining cells. We now show that in mice lacking the DNA repair enzyme alkylpurine-DNA-N-glycosylase (APNG), beta-cell necrosis was markedly attenuated after a single dose of STZ. This is most probably due to the reduction in the frequency of base excision repair-induced strand breaks and the consequent activation of poly(ADP-ribose) polymerase (PARP), which results in catastrophic ATP depletion and cell necrosis. Indeed, PARP activity was not induced in APNG(-/-) islet cells following treatment with STZ in vitro. However, 48 h after STZ treatment, there was a peak of apoptosis in the beta cells of APNG(-/-) mice. Apoptosis was not observed in PARP-inhibited APNG(+/+) mice, suggesting that apoptotic pathways are activated in the absence of significant numbers of DNA strand breaks. Interestingly, STZ-treated APNG(-/-) mice succumbed to diabetes 8 months after treatment, in contrast to previous work with PARP inhibitors, where a high incidence of beta-cell tumors was observed. In the multiple-low-dose model, STZ induced diabetes in both APNG(-/-) and APNG(+/+) mice; however, the initial peak of apoptosis was 2.5-fold greater in the APNG(-/-) mice. We conclude that APNG substrates are diabetogenic but by different mechanisms according to the status of APNG activity.

Alkylpurine-DNA-N-glycosylase knockout mice show increased susceptibility to induction of mutations by methyl methanesulfonate.

Alkylpurine-DNA-N-glycosylase (APNG) null mice have been generated by homologous recombination in embryonic stem cells. The null status of the animals was confirmed at the mRNA level by reverse transcription-PCR and by the inability of cell extracts of tissues from the knockout (ko) animals to release 3-methyladenine (3-meA) or 7-methylguanine (7-meG) from 3H-methylated calf thymus DNA in vitro. Following treatment with DNA-methylating agents, increased persistence of 7-meG was found in liver sections of APNG ko mice in comparison with wild-type (wt) mice, demonstrating an in vivo phenotype for the APNG null animals. Unlike other null mutants of the base excision repair pathway, the APNG ko mice exhibit a very mild phenotype, show no outward abnormalities, are fertile, and have an apparently normal life span. Neither a difference in the number of leukocytes in peripheral blood nor a difference in the number of bone marrow polychromatic erythrocytes was found when ko and wt mice were exposed to methylating or chloroethylating agents. These agents also showed similar growth-inhibitory effects in primary embryonic fibroblasts isolated from ko and wt mice. However, treatment with methyl methanesulfonate resulted in three- to fourfold more hprt mutations in splenic T lymphocytes from APNG ko mice than in those from wt mice. These mutations were predominantly single-base-pair changes; in the ko mice, they consisted primarily of AT-->TA and GC-->TA transversions, which most likely are caused by 3-meA and 3- or 7-meG, respectively. These results clearly show an important role for APNG in attenuating the mutagenic effects of N-alkylpurines in vivo.

O6-benzylguanine increases the sensitivity of human primary bone marrow cells to the cytotoxic effects of temozolomide.

The sensitivity of human primary bone marrow granulocyte/macrophage precursor cells to the cytotoxic effects of the methylating antitumor agent temozolomide (8-carbamoyl-3- methylimidazo[5,1-d]-1,2,3,5-tetrazin-4-[3H]-1) was investigated using an in vitro colony-forming assay. In the eight samples examined, there was a range of sensitivities with D37 values from 18.2 to > 55 microM. When cells were simultaneously exposed to the O6-alkylguanine-DNA alkyltransferase (ATase) inactivating agent, O6-benzylguanine (O6BeG; 10 microM), the cytotoxicity of temozolomide was substantially increased with D37 values between 5 and 38.5 microM. O6BeG also increased temozolomide sensitivity in the human colon carcinoma cell line, WiDr, and this was shown to correlate with the O6BeG-mediated depletion of ATase activity. Where the extent of sensitization produced by O6BeG could be calculated, there was a correlation between this and the D37 value in the absence of O6BeG (R = 0.996); thus, sensitization was more extensive in the cells that were inherently more resistant to temozolomide. These data have implications for possible increased hematological toxicity in clinical protocols designed to exploit O6BeG or other agents to deplete ATase activity in tumors cells prior to treatment of patients with temozolomide or related agents.

Association of mesenchymal cells and immunoglobulins with differentiating epithelial cells.

BACKGROUND: Mesenchymal-epithelial interactions play an important role in the physiology and pathology of epithelial tissues. Mesenchymal cells either associate with epithelium basement membrane [pericytes and perivascular monocyte-derived cells (MDC)] or reside within epithelium (MDC and T cells). Although intraepithelial mesenchymal cells were suggested to contribute to the epithelium physiology, their association with particular steps in differentiation of epithelial cells, interactions among themselves, and their fate remain unclear. We studied epitopes of mesenchymal cells and their products (immunoglobulins) in stratified epithelium of uterine ectocervix, which is one of the prototypes of complete cellular differentiation from stem into the aged cells. RESULTS: Perivascular CD14 primitive MDC associated with basal (stem) epithelial cells. Thy-1 pericytes of microvasculature secreted intercellular vesicles, which associated with Ki67 postmitotic epithelial cells expressing MHC class I. Intraepithelial T cells showed an association with veiled type MDC [dendritic cell (DC) precursors] among parabasal cells, and exhibited fragmentation after entering intermediate (mature) epithelial layers. Mature DC secreted CD68 and exhibited fragmentation after reaching mid intermediate layers. Binding of IgM was detected at the top of each layer: in the upper parabasal, upper intermediate, and most surface epithelial cells. IgG was confined to the entire superficial layer. CONCLUSIONS: These data suggest that the phylogenetically and ontogenetically developed hierarchy of mesenchymal cells (MDC, pericytes, T cells) and immunoglobulins (IgM, IgG) accompanies differentiation of epithelial cells from immature into the mature and aged phenotype. Further studies of an involvement of mesenchymal cells in the regulation of tissue homeostasis may bring novel approaches to the prevention and therapy of tissue dysfunctions characterized by permanent tissue immaturity (muscular dystrophy) or accelerated aging (degenerative diseases).

Dietary fish oil reduces O6-methylguanine DNA adduct levels in rat colon in part by increasing apoptosis during tumor initiation.

There is epidemiological, clinical, and experimental evidence that dietary fish oil, containing n-3 polyunsaturated fatty acids, protects against colon tumor development. However, its effects on colonocytes in vivo remain poorly understood. Therefore, we investigated the ability of fish oil to modulate colonic methylation-induced DNA damage, repair, and deletion. Sprague Dawley rats were provided with complete diets containing either corn oil or fish oil (15% by weight). Animals were injected with azoxymethane, and the distal colon was removed 3, 6, 9, or 12 h later. Targeted apoptosis and DNA damage were assessed by cell position within the crypt using the terminal deoxynucleotidyl transferase-mediated nick end labeling assay and quantitative immunohistochemical analysis of O6-methylguanine adducts, respectively. Localization and expression of the alkyl group acceptor, O6-methylguanine-DNA-methyltransferase, was also determined. Lower levels of adducts were detected at 6, 9, and 12 h in fish oil- versus corn oil-fed animals (P < 0.05). In addition, fish oil supplementation had the greatest effect on apoptosis in the top one-third of the crypt, increasing the apoptotic index compared with corn oil-fed rats (P < 0.05). In the top one-third of the crypt, fish oil feeding caused an incremental stimulation of apoptosis as adduct level increased. In contrast, a negative correlation between apoptosis and adduct incidence occurred with corn oil feeding (P < 0.05). Diet had no main effect (all tertiles combined) on O6-methylguanine-DNA-methyltransferase expression over the time frame of the experiment. The enhancement of targeted apoptosis combined with the reduced formation of O6-methylguanine adducts may account, in part, for the observed protective effect of n-3 polyunsaturated fatty acids against experimentally induced colon cancer.

Expression of O6-alkylguanine-DNA-alkyltransferase in situ in ovarian and Hodgkin's tumours.

The cellular expression of O6-alkylguanine-DNA-alkyltransferase (ATase) may be an important factor in determining tumour sensitivity to certain alkylating agents. In a comparative study, we have examined the inter- and intracellular distribution of ATase in tumour biopsies of a series of patients with Hodgkin's disease and ovarian cancer using a rabbit antihuman ATase antiserum. The antibody recognises the ATase protein on western blots of cell-free extracts of a number of ovarian tumours with ATase activities varying from 20 to 420 fmol/mg protein as determined by in vitro assay and there was a linear correlation between ATase activity and the intensity of the band on western blots (r = 0.993). Immunohistochemical staining was seen in all of the ovarian tumours examined and was confined to the nucleus. This is in contrast to the Hodgkin's tissue, where staining was much reduced and present in both nuclei and cytoplasm. The results suggest that in ovarian tumours the general resistance to nitrosourea chemotherapy may be related to the high cellular expression of ATase protein: this is in contrast to the more chemosensitive Hodgkin's disease. This raises the possibility that it might be feasible to predict sensitivity or resistance to these alkylating agents by immunohistochemical staining of tumour or tissue specimens.