The relationship of oncotype Dx Recurrence Score (RS) with Ki 67 in early stage breast cancer patients in a community based cancer center in rural central Nebraska

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Background: Oncotype Dx recurrence score (RS), is a prognostic and predictive test utilized for decision making in adjuvant therapy of 0-3 node/hormone receptor positive(HR+)/ HER-2-negative early breast cancer. Ki-67 is a marker of proliferating cells and is associated with prognosis and response. Immunohistological (IHC) assessment of Ki 67 expression is less expensive and with the approval of CDK inhibitors in the high risk adjuvant setting, it is increasingly being utilized in clinical decision making. A moderate to strong correlation between Ki67 and Oncotype Dx RS has been reported in the literature. We sought to examine the relationship of Ki 67 to Oncotype Dx RS in a community-based cancer center in rural central Nebraska. Methods: Forty-three consecutive postmenopausal breast cancer patients(pts) diagnosed and treated at our community based cancer center between 2020-2021 with T1–2 N0-1 M0, HR+, HER-2-negative disease were evaluated for histological type, tumor size, Nottingham grade, HR levels, Ki 67 expression (low < 10%, intermediate 10 ≥ Ki67 < 25 high ≥ 25), and Oncotype Dx RS(low <16,intermediate 16⩽RS<26), high ⩾26). Ki 67 and Oncotype Dx RS were treated as continuous variables to calculate a Pearson correlation coefficient. Results: Mean age at diagnosis was 59.4 years (range 48-89). Mean tumor diameter was 15.6 mm. 78.9% were intermediate histologic grade and 9.7% patients had lymph node involvement. Median expression of ER and PR were 90% (5-100) and 70% (0-100), respectively. The mean Ki 67 value was 17.5 (range 5-60 %), and mean Oncotype RS was 14.4 (range 4-34). There was a positive linear correlation between Ki 67 expression and Oncotype Dx RS (Pearson Correlation Coefficient=0.49, P-value <0.001). The vast majority of high Ki 67 pts (80%) had high/intermediate Oncotype RS. All pts with low Ki 67 (100%) had low/intermediate RS. Conclusions: Our community based rural cancer center data support a linear, statistically significant, positive correlation between Ki 67 and Oncotype Dx RS in early stage 0-3 node/HR+ positive breast cancer pts. Increasing use of Ki 67 testing in different clinical settings will generate more data to better define this correlation.[Table: see text]

Embedded model palliative care (PC) at a community oncology practice in central Nebraska

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Background: PC combined with cancer care has been shown to improve patient outcomes and caregiver satisfaction while lessening unnecessary health care utilization. 85% of cancer patients receive their oncology care in the communities they live. Establishing a viable and sustainable outpatient PC service in the community oncology setting is challenging and rare nationwide. We present our 18-month PC services since its implementation at Morrison Cancer Center, a community oncology practice. Methods: Cancer patients were referred to PC by oncologists for symptom management, psychosocial support, and Advanced Care Planning (APC). PC visits were provided at the oncology clinic, home, nursing home, or hospital by our PC team (APRN, Social Workers, Chaplain and RN's). Palliative Care Prognostic Index (PPI), time to PC consultation, proportion of patients --on chemotherapy, switching to hospice care, receiving chemotherapy within the last 30 days of life, visiting ER and/or being admitted to hospital within the last 30 days of life-- were studied. Results: Over an 18-month period 72 patients were referred for a total of 470 visits. Lung, pancreas, gastroesophageal, and head and neck cancers were topmost sites. PC referrals per quarter increased from an initial 4 to an 18 at 18 months. Mean time from diagnosis to PC referral was 5.6 months (range: 1-36). Referral reasons included symptom management/support (58%), goals of care (50%), and/or predetermined triggers (15%). Mean PPI score was 50% (range 30-70). All patients had ACP. While 83% of patients were able to continue on active cancer treatment, only 5% received chemotherapy within the last 30 days of life, and 4 % had two or more ER visits with or without a hospital admission. Eventually, 17% of PC patients transitioned to hospice care. Conclusions: A PC program fostering expert symptom management, seamless communication, and trusting relationships between oncologists, palliative care team, and patients, without prematurely stopping active cancer treatments, is feasible and can be incorporated into a community oncology practice as demonstrated by the growth and success of our program. Our model may set an example for similar practices in the community oncology setting.

Multiplex genomic testing (MGT): Four-year real-world experience of two community oncology practices in central rural Nebraska

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Background: MGT forms the basis of precision oncology. More and more community oncology practices are utilizing MGT to identify somatic Actionable Alterations (AA) in solid tumors. This information is increasingly being used to choose FDA and/or guideline approved treatment options, or clinical trials. Methods: From July 2014 to July 2018, MGT (Foundation Medicine) data of patients (pts) with solid tumors at two community hospital-based oncology practices in central rural Nebraska were retrospectively analyzed. Study population consisted of advanced solid tumor pts (ECOG 0-2) with an available MGT result who had progressed on standard treatment regimens. Treating community oncologists directed treatment choices based on MGT results. Results: 360 pts underwent MGT. Average (avg) turn-around time from order to reporting was 20.19 days. Reimbursements were through commercial insurance (27 %), Medicare (66%), Medicaid (3%), self-pay (2 %) and financial assistance by company (2%). Most common cancer types were non-small cell lung (27%), pancreas (9%), colon (8%), unknown primary (4%), sarcoma (4%), breast (4%), gastro-esophageal (2%) and kidney (1%). 79% of samples had at least one AA. In 69 (19%) pts these alterations were matched to one or more on/off label FDA and/or guideline approved targeted therapies. Only 26/69 pts (37%) in this group were able to have a therapy that was new. 43 (12%) of pts qualified and went on locally available clinical trials (MATCH, LUNG-MAP and TAPUR). Conclusions: Our analysis reflects a 4-year real-world MGT experience in two community oncology practices in central rural Nebraska. In addition to established barriers of cost, long turnaround time, adequate tissue, the low yield of new FDA and/or guideline approved treatments decreases the utility of MGT. Increased variety and availability of precision medicine clinical trials with improved patient access in the rural setting may improve this shortcoming.[Table: see text]

A pilot study of an HbA1c chairside screening protocol for diabetes in patients with chronic periodontitis: the dental hygienist's role

OBJECTIVE

To assess effectiveness, convenience and cost of point-of-care diabetes screenings performed by a dental hygienist for patients with periodontitis, using a diabetes risk questionnaire, periodontal findings and a glycosylated haemoglobin (HbA1c) analyser.

METHODS

A purposive sample of 50 participants with periodontitis, never diagnosed with diabetes, reporting ≥one diabetes risk factor, were administered an HbA1c test. Spearman's correlation measured relationships between HbA1c and diabetes risk test scores, numbers of missing teeth, percentage of deep pockets ≥5 mm and percentage of bleeding sites (BOP). Cost and time were assessed. Analyses used 0.05 alpha levels.

RESULTS

Thirty-two per cent (n = 16) of participants presented HbA1c values indicating prediabetes; one HbA1c value indicated type 2 diabetes, totalling 34% (N = 17). No relationships existed between HbA1c values and diabetes risk scores (rs = 0.153; P = 0.144), numbers of missing teeth (r = 0.190; P = 0.093), percentage of deep pockets (rs = -0.048; P = 0.370) or percentage of BOP sites (rs = 0.066, P = 0.324). Direct cost for each HbA1c was $9US, excluding follow-up medical diagnosis. Mean screening time including patient education was 14 min (SD = 6.2). Fifty-three per cent (n = 9 of 17) of participants with elevated HbA1c values contacted their primary healthcare provider within 2 weeks as recommended.

CONCLUSION

Point-of-care HbA1c screenings by dental hygienists were effective and convenient for identifying undiagnosed prediabetes and provide opportunity for interprofessional patient care; cost or lack of dental insurance may inhibit implementation. Identification of patients at risk for diabetes requires further evaluation.

Aging and quality control of color LCDs for radiologic imaging

Our practice has long been concerned with the effects of display quality, including color accuracy and matching among paired color displays. Three years of data have been collected on the historical behavior of color stability on our clinical displays. This has permitted an analysis of the color-aging behavior of those displays over that time. The results of that analysis show that all displays tend to yellow over time, but that they do so together. That is, neither the intra- nor inter-display color variances observed at initial deployment diverge over time as measured by a mean radial distance metric in color space (Commission Internationale d'Eclairage L', u', v' 1976). The consequence of this result is that color displays that are matched at deployment tend to remain matched over their lifetime even as they collectively yellow.

Constructing defined chromosome segmental duplications in maize

We describe the production of chromosome segmental duplications and deletions of defined length in maize. The method utilizes a collection of previously isolated transposon-induced reciprocal translocations with sequence-defined breakpoints. These balanced translocations involve a first common breakpoint at the site of transposon Ac/fAc insertions on chromosome 1S, and a second variable endpoint elsewhere in the genome. Stocks containing translocations with different endpoints on the same chromosome arms were crossed together to generate heterozygous combinations. Subsequent meiotic segregation generates gametes that contain the original balanced translocations, or pairs of translocation chromosomes that are genetically unbalanced; i.e., they contain a duplication or deletion of the affected segment. Self-pollination produces progeny plants that are genetically balanced, or that contain 0 to 4 copies of the affected segment. The chromosome constitution of progeny plants can be determined using PCR primers flanking the translocation breakpoints. In addition, plants segregating genetically unbalanced gametes exhibit significant pollen grain abnormalities and thus can be easily detected in the field. In this way, we constructed 4 different segmental tetrasomic stocks involving genomic regions of approximately 7.8, 18.7, 21, and 42.6 Mb on chromosomes 5S, 5L, 5L, and 4L, respectively. FISH analysis using specific probes located within the affected segments confirms their aneuploid composition. These and similar lines containing precisely defined segmental duplications and deletions may be useful to study the genetic impact of gene dosage.

An alternate hypothesis to explain the high frequency of "revertants" in hothead mutants in Arabidopsis

Lolle et al. reported a high frequency of genomic changes in ARABIDOPSIS plants carrying the hothead mutation and proposed that the changes observed were the result of a gene correction system mediated by a hypothetical RNA cache. Here, we propose a very different hypothesis to explain the data reported by Lolle et al. Our hypothesis is based on a relatively straightforward developmental aberration in which maternal cells ("Legacy cells") fuse with the developing embryo, resulting in a chimera, which could then give rise to the aberrant genetic segregations reported by Lolle et al.

Measurement of the absolute n p scattering differential cross section at 194 MeV

We describe a double-scattering experiment with a novel tagged neutron beam to measure differential cross sections for np backscattering to better than +/-2% absolute precision. The measurement focuses on angles and energies where the cross section magnitude and angle dependence constrain the charged pion-nucleon coupling constant, but existing data show serious discrepancies among themselves and with energy-dependent partial-wave analyses. The present results are in good accord with the partial-wave analyses, but deviate systematically from other recent measurements.

Ac transposition is impaired by a small terminal deletion

In maize, the P1-vv allele specifies variegated pericarp and cob pigmentation, and contains an Ac transposable element inserted in the second intron of the P1-rr gene. Starting from P1-vv, we recovered a new allele, called P1-vv5145, which gives an extremely light variegated pericarp and cob phenotype. The P1-vv5145 allele contains an Ac element ( Ac5145) at the same position and in the same orientation as in the progenitor P1-vv allele; however, the P1-vv5145 allele has a 2-bp deletion which removes the last nucleotide (A) from the 3' end of the Ac element, and an adjacent flanking nucleotide (C) from the p1 intron. In crosses with a Ds tester stock, P1-vv5145 shows a normal ability to induce Ds transposition; however, Ac excision from P1-vv5145 is 3800-fold less frequent than from the progenitor P1-vv allele. Our results demonstrate that the alteration of the 3' terminal base strongly impairs Ac transposition. The P1-vv5145 allele thus provides a relatively stable source of Ac transposase for controlling Ds transposition in genetic experiments. In addition, we describe two further alleles ( P1-ww7B8, P1-ww9A146-3) that contain deletions of Ac and flanking p1 gene sequences. These latter deletions are larger and involve the 5' end of the the Ac element. A model is proposed to explain the formation of one-sided deletions as a consequence of Ac transposition during replication of the element.

Mobility of polymer chains confined at a free surface

Dynamic secondary ion mass spectrometry was used to investigate the chain mobility of polystyrene (MW ranging from 4.3 to 957 kg/mol) at the free surface. The data show that the diffusion coefficient was reduced relative to the bulk value within a distance, d < or = 4R(g), from the surface and scaled as 1/N(2.5) at fixed d. These results are in excellent agreement with self-consistent field calculations of the surface segmental distribution and provide the first direct confirmation of various theoretical models that predict asymmetric segmental fluctuation which arises from surface induced orientation of polymer chains.

Tissue-specific patterns of a maize Myb transcription factor are epigenetically regulated

The maize p1 gene encodes a Myb-homologous regulator of red pigment biosynthesis. To investigate the tissue-specific regulation of the p1 gene, maize plants were transformed with constructs combining promoter and cDNA sequences of two alleles which differ in pigmentation patterns: P1-wr (white pericarp/red cob) and P1-rr (red pericarp/red cob). Surprisingly, all promoter/cDNA combinations produced transgenic plants with red pericarp and red cob (RR pattern), indicating that the P1-wr promoter and encoded protein can function in pericarp. Some of the RR patterned transgenic plants produced progeny plants with white pericarp and red cob (WR pattern), and this switch in tissue-specificity correlated with increased transgene methylation. A similar inverse correlation between pericarp pigmentation and DNA methylation was observed for certain natural p1 alleles, which have a gene structure characteristic of standard P1-wr alleles, but which confer red pericarp pigmentation and are consistently less methylated than standard P1-wr alleles. Although we cannot rule out the possible existence of tissue-specific regulatory elements within the p1 non-coding sequences or flanking regions, the data from transgenic and natural alleles suggest that the tissue-specific pigmentation pattern characteristic of the P1-wr phenotype is epigenetically controlled.

Unique design for fixed ventilated changing station

The Jackson Laboratory animal colonies present a unique challenge for the design and operation of an animal changing station that maximizes protection of animal health and welfare while also protecting the health and safety of the animal caretaker. The authors describe the modification of a fixed ventilated changing station for improved animal health, reduced ergonomic strain, and decreased allergen exposure.

Transgene-induced silencing identifies sequences involved in the establishment of paramutation of the maize p1 gene

A transgene carrying a distal enhancer element of the maize P1-rr promoter caused silencing of an endogenous P1-rr allele in the progeny of transgenic maize plants. Expression of both the transgene and the endogenous P1-rr allele was reduced in the affected plants. The silenced phenotype was observed in the progeny of seven of eight crosses involving three independent transgenic events tested (average frequency of 19%). This phenotype was associated with an induced epigenetic state of the P1-rr allele, termed P1-rr', which is characterized by increased methylation of the P1-rr flanking regions and decreased levels of P1-rr transcript. The P1-rr' epiallele is highly heritable in the absence of the inducing P1.2b::GUS transgene, and it can impose an equivalent state on a naive P1-rr allele in subsequent crosses (paramutation). In contrast, parallel experiments with two other P::GUS transgenes that contained the same basal P1-rr promoter fragment but different upstream sequences revealed no detectable silencing effect. Thus, transgenes carrying a specific enhancer fragment of the P1-rr gene promoter can trigger a paramutant state (P1-rr') of the endogenous P1-rr gene that is maintained in the absence of the inducing transgene. We discuss the potential role of the P1-rr distal enhancer element in the establishment and propagation of a paramutation system in maize.

A segmental gene duplication generated differentially expressed myb-homologous genes in maize

The myb-homologous p1 gene regulates the synthesis of flavonoid pigments in maize kernel pericarp and cob; these floral organs are greatly modified in size and shape compared with their counterparts in teosinte, the progenitor of maize. To elucidate the molecular evolution of the p1 gene in relation to its expression and possible functions in maize and teosinte, we have isolated a second maize gene (p2) that is highly homologous with the p1 gene, and a related gene (p2-t) from Zea mays subsp parviglumis. We present evidence that the maize p1 and p2 genes were generated by duplication of an ancestral p gene (p(pre)) and its downstream sequences; the duplicated 3' flanking sequences were inserted upstream of the p(pre) gene, thereby changing its transcription pattern. This model accounts for the structural organization and the observed differential expression of the p1 and p2 genes: p1 transcripts accumulate in kernel pericarp, cob, tassel glumes, and silk, whereas p2 transcripts are found in developing anther and silk. The duplication is estimated to have occurred 2.75 million years ago; subsequently, multiple retroelements have been inserted between the p1 and p2 genes. Our results demonstrate the evolution of a single gene into a compound locus containing two component genes with different tissue specificities. Expression of the p1 gene in the kernel pericarp may have provided a selective advantage during the evolution of maize kernel morphology.

Ac insertion site affects the frequency of transposon-induced homologous recombination at the maize p1 locus

The maize p1 gene regulates the production of a red pigment in the kernel pericarp, cob, and other maize floral tissues. Insertions of the transposable element Ac can induce recombination between two highly homologous 5.2-kb direct repeat sequences that flank the p1 gene-coding region. Here, we tested the effects of the Ac insertion site and orientation on the induction of recombination at the p1 locus. A collection of unique p1 gene alleles was used, which carry Ac insertions at different sites in and near the p1 locus, outside of the direct repeats, within the direct repeat sequences, and between the direct repeats, in both orientations. Recombination was scored by the numbers of colorless pericarp sectors (somatic frequency) and heritable mutations (germinal frequency). In both the somatic and germinal tests, the frequency of homologous recombination is significantly higher when Ac is inserted between the direct repeats than when Ac is inserted either within or outside the repeats. In contrast, Ac orientation had no significant effect on recombination frequency. We discuss these results in terms of the possible mechanisms of transposon-induced recombination.

A segmental gene duplication generated differentially expressed myb-homologous genes in maize

The myb-homologous p1 gene regulates the synthesis of flavonoid pigments in maize kernel pericarp and cob; these floral organs are greatly modified in size and shape compared with their counterparts in teosinte, the progenitor of maize. To elucidate the molecular evolution of the p1 gene in relation to its expression and possible functions in maize and teosinte, we have isolated a second maize gene (p2) that is highly homologous with the p1 gene, and a related gene (p2-t) from Zea mays subsp parviglumis. We present evidence that the maize p1 and p2 genes were generated by duplication of an ancestral p gene (p(pre)) and its downstream sequences; the duplicated 3' flanking sequences were inserted upstream of the p(pre) gene, thereby changing its transcription pattern. This model accounts for the structural organization and the observed differential expression of the p1 and p2 genes: p1 transcripts accumulate in kernel pericarp, cob, tassel glumes, and silk, whereas p2 transcripts are found in developing anther and silk. The duplication is estimated to have occurred 2.75 million years ago; subsequently, multiple retroelements have been inserted between the p1 and p2 genes. Our results demonstrate the evolution of a single gene into a compound locus containing two component genes with different tissue specificities. Expression of the p1 gene in the kernel pericarp may have provided a selective advantage during the evolution of maize kernel morphology.

Hierarchical patterns of transgene expression indicate involvement of developmental mechanisms in the regulation of the maize P1-rr promoter

The maize P1-rr gene encodes a Myb-homologous transcription factor that regulates the synthesis of red flavonoid pigments. Maize plants transformed with segments of the P1-rr promoter driving a GUS reporter gene exhibit significant variation in transgene expression, both between independent transformation events and among sibling plants derived from a single event. Interestingly, variability in spatial expression is not random; rather, transgene activity occurs predominantly in five patterns that fit a hierarchy: expression is most common in kernel pericarp, with sequential addition of expression in cob glumes, husk, silk, and tassel. The hierarchical expression pattern of P-rr::GUS transgenes suggests a possible model for developmental regulation of the P1-rr gene. Our results demonstrate that variability in transgene expression, a common occurrence in transgenic plant studies, can be informative if adequately analyzed to uncover underlying patterns of gene expression.

Complex structure of a maize Myb gene promoter: functional analysis in transgenic plants

The maize P gene encodes a Myb-like transcription factor that regulates synthesis of red flavonoid pigments in floral organs. To study the transcriptional regulation of the P gene, candidate regulatory sequences of the P1-rr gene promoter were identified by Ac insertional mutagenesis and subjected to functional testing in transgenic maize plants. The results indicate that a 561 bp fragment (Pb) encompassing the transcription start site (-235 to +326) supports weak expression of a GUS reporter gene in floral organs, including husk, silk, kernel pericarp, cob and male inflorescence. Two other fragments, located approximately 1 and 5 kb 5' of the transcription start site, increased the levels of GUS activity in floral tissues and thus appear to contain enhancer elements. All of the tested constructs gave similar patterns of GUS expression, suggesting that the 561 bp Pb fragment that is common among the transgene constructs contains regulatory elements that promote activation in floral organs. The basal promoter and proximal enhancer fragments contain putative binding sites for bZip regulatory factors, and a complex arrangement of palindromes including a large inverted repeat of two tRNA-like genes. Possibly, interconversions between linear and cruciform conformations of the palindromes may affect protein/DNA interactions and thereby modulate P1-rr expression.

Comparison of standard and second harmonic B-mode sonography in the detection of segmental renal infarction with sonographic contrast in a rabbit model

This study compares contrast-enhanced fundamental and second harmonic B-mode sonography using a rabbit renal infarct model. Segmental renal infarctions were produced in 13 rabbits by embolizing a 0.7 mm bead into the renal artery 1 day prior to imaging. An ultrasonographic unit equipped with an L10-5 transducer and second harmonic imaging capability was used. Real-time recordings were made during the injection of 0.5 ml of an experimental formulation of a perfluorohexane vapor-stabilized microbubble (AF0145) given into the ear vein, and the imaging technique alternated between standard and harmonic imaging every 20 s. Each rabbit received two injections 1 h apart. To control for the effect of peak bolus enhancement, the initial imaging technique used for the first injection was randomized, and the other technique was used initially for the second injection. The videointensity difference between the infarcted and the normal cortex was then calculated and evaluated as a function of time. The infarcted segment could not be seen before administration of contrast agent with either technique. Although the infarction could be seen after injection of contrast agent with either technique, image contrast and contrast duration were nearly 75% greater for the harmonic technique than for the standard technique. AF0145 allows the visualization of segmental renal infarction on standard B-mode imaging. The second harmonic B-mode technique significantly increases image contrast and contrast duration.

Intrachromosomal homologous recombination in Arabidopsis induced by a maize transposon

In plants, the frequency of spontaneous intrachromosomal homologous recombination is low. Here, we show that a maize transposable element greatly stimulates intrachromosomal homologous recombination between direct repeat sequences in Arabidopsis. Plants were transformed with a construct (GU-Ds-US) containing a Ds (Dissociation) transposable element inserted between two partially deleted GUS reporter gene segments. Homologous recombination between the overlapping GUS fragments generates clonal sectors visible upon staining for GUS activity. Plants containing the GU-Ds-US construct and a source of Ac (Activator) transposase showed an over 1000-fold increase in the incidence of recombination relative to plants containing the same construct but lacking transposase. Transposon-induced recombination was observed in vegetative and floral organs, and several germinally transmitted events were recovered. Transposon-induced recombination appears to be a general phenomenon in plants, and thus may have contributed to genome evolution by inducing deletions between repeated sequences.

Molecular characterization of a mutable pigmentation phenotype and isolation of the first active transposable element from Sorghum bicolor

Accumulation of red phlobaphene pigments in sorghum grain pericarp is under the control of the Y gene. A mutable allele of Y, designated as y-cs (y-candystripe), produces a variegated pericarp phenotype. Using probes from the maize p1 gene that cross-hybridize with the sorghum Y gene, we isolated the y-cs allele containing a large insertion element. Our results show that the Y gene is a member of the MYB-transcription factor family. The insertion element, named Candystripe1 (Cs1), is present in the second intron of the Y gene and shares features of the CACTA superfamily of transposons. Cs1 is 23,018 bp in size and is bordered by 20-bp terminal inverted repeat sequences. It generated a 3-bp target site duplication upon insertion within the Y gene and excised from y-cs, leaving a 2-bp footprint in two cases analyzed. Reinsertion of the excised copy of Cs1 was identified by Southern hybridization in the genome of each of seven red pericarp revertant lines tested. Cs1 is the first active transposable element isolated from sorghum. Our analysis suggests that Cs1-homologous sequences are present in low copy number in sorghum and other grasses, including sudangrass, maize, rice, teosinte, and sugarcane. The low copy number and high transposition frequency of Cs1 imply that this transposon could prove to be an efficient gene isolation tool in sorghum.

Genome rearrangements by nonlinear transposons in maize

Transposable elements have long been considered as potential agents of large-scale genome reorganization by virtue of their ability to induce chromosomal rearrangements such as deletions, duplications, inversions, and reciprocal translocations. Previous researchers have shown that particular configurations of transposon termini can induce chromosome rearrangements at high frequencies. Here, we have analyzed chromosomal rearrangements derived from an unstable allele of the maize P1 (pericarp color) gene. The progenitor allele contains both a full-length Ac (Activator) transposable element and an Ac terminal fragment termed fAc (fractured Ac) inserted in the second intron of the P1-rr gene. Two rearranged alleles were derived from a classical maize ear twinned sector and were found to contain a large inverted duplication and a corresponding deficiency. The sequences at the junctions of the rearrangement breakpoints indicate that the duplication and deletion structures were produced by a single transposition event involving Ac and fAc termini located on sister chromatids. Because the transposition process we describe involves transposon ends located on different DNA molecules, it is termed nonlinear transposition (NLT). NLT can rapidly break and rejoin chromosomes and thus could have played an important role in generating structural heterogeneity during genome evolution.

Voice and speech characteristics of persons with Parkinson's disease pre- and post-pallidotomy surgery: preliminary findings

Pallidotomy surgery, lesioning the globus pallidus internal, has been performed to alleviate Parkinsonian symptoms and drug-induced dyskinesias. Improvements in limb motor function have been reported in recent years following pallidotomy surgery. The purpose of this preliminary study was to determine the effect of pallidotomy surgery on select voice and speech characteristics of 6 patients with Parkinson's disease. Acoustic measures were analyzed pre-pallidotomy surgery and again at 3 months following surgery. Preliminary findings indicated that all participants demonstrated positive changes in at least one acoustic measure; 2 of the participants consistently demonstrated positive changes in phonatory and articulatory measures, whereas 3 participants did not consistently demonstrate positive changes postsurgery. The results are discussed relative to the differential effects observed across participants.

Activated sulfonamides are cleaved by glutathione-S-transferases

In preclinical pharmacokinetic studies and in in vitro rat, dog, and human primary hepatocyte incubations, the sulfonamide (-NH-SO(2)-) bond of a potent inhibitor of the HIV-1 protease containing the p-cyanopyridinyl moiety (PNU-109112), undergoes metabolic cleavage to form the corresponding amine metabolite (PNU-143070). Strikingly, a compound, PNU-140690, obtained by substituting the cyanopyridinyl group of PNU-109112 with a trifluoropyridinyl moiety, was stable under the same in vivo and in vitro conditions used for PNU-109112. The apparent "sulfonamidase activity" present in liver was localized to the cytosolic fraction and shown to be an enzyme-mediated reaction requiring reduced glutathione (GSH). The enzyme responsible was purified in a single step on a GSH immobilized gel and was identified as glutathione-S-transferase (GST) by sequence analysis of peptides obtained by tryptic digestion of the purified protein. Moreover, a mixture of GST isoenzymes purified from rat liver, and three recombinant human GST isoforms, A1-1, M1-1, and P1-1, were active toward PNU-109112 sulfonamide cleavage; the three isoforms exhibited differential rates of PNU-109112 cleavage, demonstrating isoenzyme selectivity.

Mechanism, structure-activity studies, and potential applications of glutathione S-transferase-catalyzed cleavage of sulfonamides

The mechanism of sulfonamide cleavage of PNU-109112, a potent HIV-1 protease inhibitor, by glutathione-S-transferase (GST) was investigated in the presence of reduced GSH. GST-catalyzed sulfonamide cleavage takes place via the nucleophilic attack of GSH on the pyridine moiety of the substrate with formation of the GS-para-CN-pyridinyl conjugate, the corresponding amine, and sulfur dioxide. Structure activity studies with a variety of sulfonamides indicate that an electrophilic center alpha to the sulfonyl group is required for cleavage. Substituents that withdraw electron density from the carbon atom alpha- to the sulfonyl group facilitate nucleophilic attack by the GS(-) thiolate bound to GST. The rate of sulfonamide cleavage is markedly affected by the nature of the electrophilic group; replacement of para-CN by para-CF(3) on the pyridine ring of PNU-109112 confers stability against sulfonamide cleavage. On the other hand, stability of sulfonamides is less dependent on the nature of the amine moiety. These principles can be applied to the synthesis of sulfonamides, labile toward cellular GST, that may serve as prodrugs for release of bioactive amines. Tumors are particularly attractive targets for these sulfonamide prodrugs as GST expression is significantly up-regulated in many cancer cells. Another potential application could be in organic synthesis, where protection of amines as the corresponding activated sulfonamides can be reversed by GST/GSH under mild conditions.

Multi-agent reinforcement learning: weighting and partitioning

This article addresses weighting and partitioning, in complex reinforcement learning tasks, with the aim of facilitating learning. The article presents some ideas regarding weighting of multiple agents and extends them into partitioning an input/state space into multiple regions with differential weighting in these regions, to exploit differential characteristics of regions and differential characteristics of agents to reduce the learning complexity of agents (and their function approximators) and thus to facilitate the learning overall. It analyzes, in reinforcement learning tasks, different ways of partitioning a task and using agents selectively based on partitioning. Based on the analysis, some heuristic methods are described and experimentally tested. We find that some off-line heuristic methods perform the best, significantly better than single-agent models.