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C Merril

Publications and source records attributed to C Merril.

14 recordsLinked to original sources
PubMed2004

Genomic analysis of bacteriophages SP6 and K1-5, an estranged subgroup of the T7 supergroup.

We have determined the genome sequences of two closely related lytic bacteriophages, SP6 and K1-5, which infect Salmonella typhimurium LT2 and Escherichia coli serotypes K1 and K5, respectively. The genome organization of these phages is almost identical with the notable exception of the tail fiber genes that confer the different host specificities. The two phages have diverged extensively at the nucleotide level but they are still more closely related to each other than either is to any other phage currently characterized. The SP6 and K1-5 genomes contain, respectively, 43,769 bp and 44,385 bp, with 174 bp and 234 bp direct terminal repeats. About half of the 105 putative open reading frames in the two genomes combined show no significant similarity to database proteins with a known or predicted function that is obviously beneficial for growth of a bacteriophage. The overall genome organization of SP6 and K1-5 is comparable to that of the T7 group of phages, although the specific order of genes coding for DNA metabolism functions has not been conserved. Low levels of nucleotide similarity between genomes in the T7 and SP6 groups suggest that they diverged a long time ago but, on the basis of this conservation of genome organization, they are expected to have retained similar developmental strategies.

Bacteriophage T7↗
PubMed2000

A prospective study of serum pseudocholinesterase levels in patients with chronic spinal pain: a preliminary study.

STUDY DESIGN: One-dimensional polyacrylamide gel electrophoresis was used to study serum esterase enzymatic activity in three groups of patients and one group of normal volunteers. OBJECTIVES: To determine whether there is a statistically significant correlation between variations of serum pseudocholinesterase and the perception of pain in patients with chronic spinal pain. SUMMARY OF BACKGROUND DATA: Changes in levels of cholinesterase in the extracellular space of the brain and in the cerebral spinal fluid have been found to be associated in animal pain experimentation. METHODS: Ninety-three surgical patients with chronic spinal pain, six surgical control subjects operated for conditions not associated with pain, 21 normal control volunteers, and nine disabled patients receiving monetary benefits were studied. The patients were analyzed for a period of time by rating the perception of their pain with a visual assessment score at the time venous blood was drawn. Serum samples were prepared, serum pseudocholinesterase was monitored, separated, and quantified according to Allen et al.5 Paired sample t tests were used to statistically evaluate the data. RESULTS: A trend of correlation was noted between preoperative serum pseudocholinesterase levels and visual assessment score: serum pseudocholinesterase levels increased as visual assessment score increased. The mean preoperative serum pseudocholinesterase level of chronic spinal pain patients (1313; SE = 26), which was significantly higher than the mean levels of the normal control volunteers (941; SE = 24; P<0.001) and that of surgical control subjects (1018; SE = 63; P <0.01), decreased significantly with anesthesia (P<0.005). The mean preoperative serum pseudocholinesterase level of the surgical controls, however, remained unchanged with anesthesia. A correlation demonstrated between visual assessment score and serum pseudocholinesterase in chronic spinal pain patients was not observed in six of nine patients receiving disability payments for more than a year. CONCLUSIONS: Measurements of quantitative alterations of serum pseudocholinesterase levels may be useful in the treatment of patients with chronic spinal pain.

Adult↗
PubMed1996

A World Wide Web (WWW) server database engine for an organelle database, MitoDat.

We describe a simple database search engine "dbEngine" which may be used to quickly create a searchable database on a World Wide Web (WWW) server. Data may be prepared from spreadsheet programs (such as Excel, etc.) or from tables exported from relationship database systems. This Common Gateway Interface (CGI-BIN) program is used with a WWW server such as available commercially, or from National Center for Supercomputer Algorithms (NCSA) or CERN. Its capabilities include: (i) searching records by combinations of terms connected with ANDs or ORs; (ii) returning search results as hypertext links to other WWW database servers; (iii) mapping lists of literature reference identifiers to the full references; (iv) creating bidirectional hypertext links between pictures and the database. DbEngine has been used to support the MitoDat database (Mendelian and non-Mendelian inheritance associated with the Mitochondrion) on the WWW.

Computer Communication Networks↗
PubMed1992

Increased phosphorylation of elongation factor 2 in Alzheimer's disease.

Elongation factor 2 (EF-2) is a phosphoprotein that mediates the translocation step of elongation during protein synthesis. We investigated its phosphorylation to characterize translational regulation of gene expression in Alzheimer's disease. EF-2 was identified on two-dimensional (2D) gels of brain homogenates by analyzing immunoblots with EF-2-specific antibody (M(r) 96,000; pI 6.8). Four distinct charge variant isoforms were observed. We identified the two most acidic isoforms as being the phosphorylated forms by incorporation of radiolabeled phosphate. The phosphorylation of EF-2 in control and Alzheimer's disease (AD) brain was directly measured as the distribution of the four polypeptides on silver stained 2D gels. The ratio of the phosphorylated forms to unphosphorylated forms was elevated 45% in AD homogenates compared to controls (1.07 +/- 0.18; n = 9 vs 0.73 +/- 0.20; n = 6; P less than 0.004) which indicated an increased phosphorylation of AD EF-2. The phosphorylation exhibited specificity to the disease in that it was observed in affected areas (cortex and hippocampus) but not in an unaffected area (thalamus) of the same brains. Because phosphorylation of EF-2 inhibits protein synthesis, the observed AD-associated phosphorylation of EF-2 is consistent with the reduced in vitro activity of polysomes isolated from AD tissues that we have previously reported.

Adenosine Diphosphate Ribose↗
PubMed1991

Increased synthesis and accumulation of heat shock 70 proteins in Alzheimer's disease.

Postmortem cortical tissues from Alzheimer's disease cases were found to contain significantly higher levels of the heat shock proteins hsp 72 and hsp 73 than control cortical tissues. This elevation was associated with the disease pathology in that it was not observed in Alzheimer's disease cerebella and was not correlated with perimortem characteristics such as age or cause of death of the patient or postmortem interval of the brain tissue. Examination of polysome translation products on two dimensional gels and by immunoprecipitation indicated that the syntheses of hsp 72/73 were increased in Alzheimer's disease tissues. In addition, immunoprecipitation of newly synthesized hsp 72 showed that numerous other nascent polypeptides were co-precipitated, which indicates an irreversible cotranslational association with the hsp 72. These results indicate that induction of specific heat shock proteins is associated with Alzheimer's disease and that cotranslational processes are affected by this induction.

Aged↗
PubMed1989

Strategies and techniques for testing the precision, reliability and reproducibility of computerized two-dimensional gel electrophoresis analysis systems.

A set of test procedures is described for evaluating the reliability, precision and reproducibility of computer systems designed to analyze two-dimensional gel electrophoretograms. The Elsie 4 gel analysis system (Analyt. Biochem., 169, 49-70 (1988) is used to demonstrate the use of these tests. Three major groups of tests are described: analysis of the scanner; analysis of mathematically constructed model gels; and analysis of real gel images. Scanner tests involve evaluating the stability and reproducibility of the scanner. The tests consist primarily of measuring the output of the scanner over a time period to determine its stability, and evaluating the consistency of the scanner at different points in the scanning field. Commonly encountered real gel situations are simulated and analyzed by arranging computer-generated 'ideal spots' in different ways. With such gels we can determine such things as the ability of the computer system to separate closely resolved and/or shoulder spots; whether or not streaks and/or smears are handled correctly; how random noise affects measurements; and, in idealized situation, the accuracy of the quantitation. The idealized spots are generated using the two-dimensional Gaussian as a model of density distribution; other spot models can be used. The Elsie 4 system is capable of finding virtually any spot (if detection parameters are set low enough), and of resolving different-sized spots whose peaks are separated by one and one-half their mean half width). The most significant tests are done on a set of actual gels.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoradiography↗
PubMed1987

Loss of pirenzepine regional selectivity following solubilization and partial purification of the putative M1 and M2 muscarinic receptor subtypes.

Pirenzepine inhibition of [3H]N-methylscopolamine ([3H]NMS) binding was studied in membranous, digitonin-solubilized, and partially purified muscarinic receptors from bovine cortex, an area of the brain rich in the putative M1 muscarinic receptor subtype, and from pons-medulla, an area rich in the putative M2 subtype. In accord with previous work, we found that pirenzepine bound to membranous receptors from cortex with an IC50 that was over one order of magnitude lower than to receptors from pons-medulla. After digitonin solubilization, however, this regional selectivity was significantly reduced. In receptors from pons-medulla, the IC50 for pirenzepine inhibition of [3H]NMS was reduced from 2.1 +/- 0.7 X 10(-6) M in membrane-bound receptors, to 4.3 +/- 0.3 X 10(-7) M after solubilization, whereas in receptors from cortex, the IC50 remained unchanged after solubilization. The solubilized receptors from both brain areas maintained their binding characteristics after partial purification over an ABT-Sepharose affinity column and a hydroxylapetite column. These findings raise the possibility that the different pirenzepine binding characteristics used to define M1 and M2 receptor subtypes are not inherent in the receptor protein itself, but may be due to coupling factors such as effector proteins, phospholipids or cytoskeletal proteins which could be associated with the membranous receptor and become dissociated from the receptor after solubilization.

Animals↗
PubMed1982

Changes in gene expression accompanying chemically-induced malignant transformation of human fibroblasts.

The modulation of gene expression accompanying neoplastic transformation has been assessed by computerized microdensitometry or autoradiographic patterns of [35S]methionine labeled polypeptides separated by two-dimensional polyacrylamide gel electrophoresis. Nearly 1000 polypeptide species of parent diploid human fibroblasts (KD strain) and clonally-derived malignant fibroblasts (HUT-14 strain) were compared. HUT-14 fibroblasts express a mutation in one of the two functional beta-actin genes and possess properties that distinguish them as neoplastic cells. Of the 700 more abundant polypeptides measured, 13 were lost and 14 were gained following this neoplastic transformation. It is estimated that less than or equal to 2% of the genes expressing abundant polypeptides were either activated or shut off, but at least 32% were modulated quantitatively as a consequence of this neoplastic transformation. Classes of "highly variable" and "marginally variable" polypeptides were assigned. Among the "highly variable" polypeptides, two related species barely detectable in KD parental cells were synthesized at a 25-31-fold higher rate in the transformed cells, and the cell-associated and extracellular matrix forms of fibronectin were each diminished by greater than 90%. Principles emerging from this study may form a basis for interpretation of the role of individual genes in the expression of neoplastic characteristics of HUT-14 cells.

Autoradiography↗
PubMed1982

Actin mutations in a human fibroblast model for carcinogenesis.

We assessed the modulation of gene expression accompanying neoplastic transformation by computerized microdensitometry of autoradiographic patterns of [35S]-methionine-labeled polypeptides separated by two-dimensional polyacrylamide gel electrophoresis. Nearly 1000 polypeptide species of parent diploid human fibroblasts (KD strain) and clonally-derived malignant fibroblasts (HUT-14 strain) were compared. We found that the neoplastic HUT-14 fibroblasts express a mutation in one of the two functional beta-actin genes. In addition, of the 700 more-abundant polypeptides measured, 13 were lost and 14 new ones gained after this neoplastic transformation. We estimate that although 2% of fewer of the genes expressing abundant polypeptides were either activated or shut off, at least 32% were modulated quantitatively. A substrain of HUT-14--HUT-14T--shows increased tumorigenicity, producing larger, faster-growing fibrosarcomas in the nude mouse than does the present parent HUT-14 strain, and with fewer inoculated cells. This increase in tumorigenicity is accompanied by three subsequent changes in the mutant beta-actin polypeptide expression. A more variant mutant actin species is synthesized in HUT-14T, which differs from the original mutant polypeptide by (i) one additional negative net charge, (ii) a short half-life in the cell, (iii) a greatly diminished ability to incorporate into the detergent-resistant cytoskeleton, (iv) a decrease in affinity for deoxyribonuclease I (EC 3.1.21.1), and (v) a faster rate of synthesis. Our results suggest that a second-site mutation in the mutant beta-actin of HUT-14 was selected for during a subcloning step in the presence of 6-thioguanine before derivation of the HUT-14T substrain. This apparent mutation and two subsequent defective beta-actin expressions are accompanied by incremental increases of malignant potential.

Actins↗
PubMed1980

Protein abnormalities in macrophages bearing asbestos.

Computerized techniques for the evaluation of O'Farrell two-dimensional electrophoretic gels have been applied to proteins derived from asbestos bearing macrophages. Preliminary results indicate definite changes in the protein content of cells depending on fiber phagocytosis.

Animals↗
PubMed1978

Interaction of RNA polymerase and rho in transcription termination: coupled ATPase.

We have previously described temperature sensitive rho mutants of Escherichia coli (e.g., rho15) that are defective in transcription termination at various signals, including an IS2 DNA insertion in the gal operon [Das, A., Court, D. & Adhya, S. (1976) Proc. Natl. Acad. Sci. USA, 73, 1959-1963]. In this paper, we report the isolation of mutants altered in the beta subunit of RNA polymerase (a class of Rifampicin-resistant mutants), which restore gal IS2 polarity in the rho 15 strain. It has been shown that one of these suppressor RNA polymerases (rpoB101) requires rho to terminate transcription of phage lambda mRNA. In contrast to the wild type RNA polymerase, the suppressor RNA polymerase also terminates lambda mRNA transcription in the presence of rho15 protein. We have isolated new rho mutants (e.g., rho112) that are defective in transcription termination in the rpoB101 strain. These results strongly support the notion that rho and RNA polymerase interact functionally during transcription termination. We have shown that rho15 catalyzes ATP hydrolysis during transcription with rpoB101 RNA polymerase, but not with wild-type RNA polymerase. Because rho 15 protein hydrolyzes ATP in the presence of free RNA, we suggest that rho may recognize the 3'-OH end of RNA. During transcription, this recognition involves an interaction with RNA polymerase, resulting in the displacement of the polymerase and the release of the nascent mRNA.

Adenosine Triphosphatases↗