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J H Wright

Publications and source records attributed to J H Wright.

At least 37 records · Page 2Linked to original sources
PubMed1992

Saccharomyces telomeres assume a non-nucleosomal chromatin structure.

The chromatin structures of the telomeric and subtelomeric regions on chromosomal DNA molecules in Saccharomyces cerevisiae were analyzed using micrococcal nuclease and DNAse I. The subtelomeric repeats X and Y' were assembled in nucleosomes. However, the terminal tracts of C1-3A repeats were protein protected in a particle larger than a nucleosome herein called a telosome. The proximal boundary of the telosome was a DNase I hypersensitive site. This boundary between the telosome and adjacent nucleosomes was completely accessible to Escherichia coli dam methylase when this enzyme was expressed in yeast, whereas a site 250 bp internal to the telomeric repeats was relatively inaccessible. Telosomes could be cleaved from chromosome ends with nuclease and solubilized as protein-DNA complexes. Immunoprecipitation of chromosomal telosomes with antiserum to the RAP1 protein indicated that RAP1 was one component of isolated telosomes. Thus, the termini of chromosomal DNA molecules in yeast are assembled in a non-nucleosomal structure encompassing the entire terminal C1-3A tract. This structure is separated from adjacent nucleosomes by a region of DNA that is highly accessible to enzymes.

Chromatin↗
PubMed1992

Altered phosphorylation of free and bound forms of monkey p53 and simian virus 40 large T antigen during lytic infection.

We have identified the phosphorylation sites in monkey p53 as well as specific changes in the phosphorylation state of free and complexed forms of simian virus 40 (SV40) large T antigen (T) and monkey p53 isolate from SV40 lytically infected CV1 cells. Phosphopeptide analyses of free T and p53 (To and p53o) and complexed T and p53 (T+ and p53+) fractions indicated several quantitative increases in the specific phosphorylation of complexed forms of both proteins. The N terminus of monkey p53+ is phosphorylated at Ser-9, Ser-15, Ser-20, either Ser-33 or Ser-37, and at least one of Ser-90 to Ser-99. The C-terminal sites are Ser-315 and Ser-392. On comparing p53+ with p53o, we found that labeling of the two N-terminal phosphotryptic peptides encompassing residues 1 to 20 and 33 to 101 was increased fivefold and that Ser-315 was sevenfold more labeled than was Ser-392. When T+ was compared with To, the N-terminal peptide containing phosphorylation sites Ser-106 through Thr-124 was twofold more labeled, the peptide containing Ser-657 through Ser-679 was sixfold more labeled and contained up to four phosphorylated serine residues, and Ser-639 and Thr-701 appeared unchanged. Overall, T+ molecules appeared to contain 3.5 mol more of labeled phosphate than did To, with the N-terminal peptide appearing fully phosphorylated. The phosphopeptide patterns obtained for lytic T+ and To fractions were nearly identical to those found for wild-type SV40 T (stably complexed with mouse p53) and mutant 5080 T (defective for p53 binding) expressed in transformed C3H10T1/2 cells (L. Tack, C. Cartwright, J. Wright, A. Srinivasan, W. Eckhart, K. Peden, and J. Pipas, J. Virol. 63:3362-3367, 1989). These results indicate that increases in specific phosphorylation sites in both T+ and p53+ correlate with the association of T with p53. The enhanced phosphorylation state may be a consequence of complex formation between T and p53 or reflect an increased affinity of p53 for highly phosphorylated forms of T.

Amino Acid Sequence↗
PubMed1990

RAP1 protein interacts with yeast telomeres in vivo: overproduction alters telomere structure and decreases chromosome stability.

The protein encoded by the RAP1 gene of S. cerevisiae binds in vitro to a consensus sequence occurring at a number of sites in the yeast genome, including the repeated sequence C2-3A(CA)1-6 found at yeast telomeres. We present two lines of evidence for the in vivo binding of RAP1 protein at telomeres: first, RAP1 is present in telomeric chromatin and second, alterations in the level of RAP1 protein affect telomere length. The length changes seen with under- and overexpression of RAP1 are consistent with the interpretation that RAP1 binding to telomeres protects them from degradation. Unexpectedly, overproduction of the RAP1 protein was also shown to decrease greatly chromosome stability, suggesting that RAP1 mediates interactions that have a more global effect on chromosome behavior than simply protecting telomeres from degradation. Such interactions may involve telomere associations both with other telomeres and/or with structural elements of the nucleus.

Base Sequence↗
PubMed1990

Infection of CV1 cells expressing the polyoma virus middle T antigen or the SV40 agnogene product with simian virus 40 host-range mutants.

SV40 viruses bearing mutations at the carboxy-terminus of large T antigen exhibit a host-range phenotype: such viruses are able to grow in BSC monkey kidney cells at 37 degrees C, but give at least 10,000-fold lower yields than wild type virus in BSC cells at 32 degrees C or in CV1 monkey kidney cells at either temperature. The block to infection in the nonpermissive cell type occurs after the onset of viral DNA replication. Infectious progeny virions are produced at very low efficiency. Although capsid proteins are synthesized at decreased levels, this does not account for the magnitude of the defect. Presumably some step of virion assembly or maturation is affected in these mutants. We have previously reported that the viral agnogene product, a protein thought to be involved in viral assembly or release, fails to accumulate in CV1 cells infected with host-range mutants. In polyoma virus the middle T antigen plays a role in virion maturation by influencing the phosphorylation of capsid proteins. In this communication we show that host-range mutants fail to undergo productive infection of CV1 cells expressing middle T antigen. These mutants do form plaques on an agnoprotein-expressing cell line. However, the agnoprotein does not seem to act by correcting the mutational block but rather increases the efficiency of plaque formation.

Animals↗
PubMed1989

Relationships among nortriptyline, 10-OH(E)nortriptyline, and 10-OH(Z)nortriptyline steady-state plasma levels and nortriptyline dosage.

The postulated therapeutic activity of nortriptyline metabolites has prompted investigation of dosage adjustments based on plasma levels of nortriptyline (NT) and its metabolites. The method assumes that metabolite concentrations vary independently of nortriptyline concentrations among patients. This study tests that assumption and investigates different means of obtaining metabolite concentrations. Forty-two psychiatric inpatients were divided into three maintenance dose groups: 50, 100, and 150 mg NT/day. After a 28-day study for each inpatient, steady-state plasma concentrations for days 14, 18, 21, 25, and 28 were determined. Concentrations were averaged for each patient. Nortriptyline concentrations did not correlate well with corresponding 10-OH(E)nortriptyline (p greater than 0.05) or 10-OH(Z)nortriptyline concentrations (r2 = 0.31, p less than 0.05). Concentrations of 10-OH(E)nortriptyline did not correlate well with corresponding 10-OH(Z)nortriptyline concentrations (r2 = 0.236, p less than 0.05). Neither dose/body weight nor obesity were good predictors of individual concentrations of nortriptyline, 10-OH(E)nortriptyline, or 10-OH(Z)nortriptyline or even the sum of the three. In conclusion, optimal drug therapy may involve dosage adjustments according to the combined plasma levels of nortriptyline and metabolites. Assurance of obtaining certain plasma concentrations requires plasma level monitoring.

Body Weight↗
PubMed1989

The p53 complex from monkey cells modulates the biochemical activities of simian virus 40 large T antigen.

We have compared the ATPase, DNA-binding, and helicase activities of free simian virus 40 (SV40) large T antigen (To) and T antigen complexed with cellular p53 (T+p53). Each activity is essential for productive viral infection. The T+p53 and To fractions were prepared by sequential immunosorption of infected monkey cells with monoclonal antibodies specific for p53 and T antigen. The immune-complexed T fractions were then assayed in parallel. For ATP hydrolysis, the Vmax for T+p53 was 143 nmol of ADP per min per mg of protein, or 18-fold greater than for To. ATP had no effect on the stability of the T+p53 complex. The T+p53 complex was significantly more active than To in hydrolyzing dATP, dGTP, GTP, and UTP. Of the nucleotide substrates tested, the greatest relative increase (T+p53/To) was in hydrolyzing dGTP and GTP. In DNase footprinting assays performed under replication conditions, the T+p53 complex protected regions I, II, and III of origin DNA while equivalent amounts of To protected only regions I and II. Region III is known to contribute to the efficiency of DNA replication and contains the SP1-binding sites of the early viral promoter. The T+p53 fraction was also a more efficient helicase than To, especially with a GC-rich primer and template. Thus, the T+p53 complex has enhanced ATPase, GTPase, DNA-binding, and helicase activities. These findings imply that complex formation between cellular monkey p53 and SV40 T antigen modulates a number of essential activities of T in SV40 productive infection.

Adenosine Triphosphatases↗
PubMed1989

Alterations in the structure of new and old forms of simian virus 40 large T antigen (T) defined by age-dependent epitope changes: new T is the same as ATPase-active T.

The reactivity of simian virus 40 large T antigen labeled under pulse-chase conditions towards 22 antibodies was measured. Changes in epitope reactivity occurred in several domains of T as it matured, defining major structural alterations that distinguished mature from new molecules. New T reacted best with the same antibodies that bind and inhibit ATPase-active T. These antibodies thus can distinguish new T as a distinct structural and functional form.

Adenosine Triphosphatases↗
PubMed1989

Properties of a simian virus 40 mutant T antigen substituted in the hydrophobic region: defective ATPase and oligomerization activities and altered phosphorylation accompany an inability to complex with cellular p53.

We have analyzed the biochemical properties of a nonviable simian virus 40 (SV40) mutant encoding a large T antigen (T) bearing an amino acid substitution (Pro-584-Leu) in its hydrophobic region. Mutant 5080 has an altered cell type specificity for transformation (transforming mouse C3H10T1/2 but not rat REF52 cells), is defective for viral DNA replication, and encodes a T that is unable to form a complex with the cellular p53 protein (K. Peden, A. Srinivasan, J. Farber, and J. Pipas, Virology 168:13-21, 1989). In this article, we show that 5080-transformed C3H10T1/2 cell lines express an altered T that is synthesized at a significantly higher rate but with a shorter half-life than normal T from wild-type SV40-transformed cells. 5080 T did not oligomerize beyond 5 to 10S in size compared with normal T, which oligomerized predominantly to 14 to 20S species. In addition, the 5080 T complex had significantly decreased ATPase activity and had a 10-fold-lower level of in vivo phosphorylation compared with that of normal T. Two-dimensional phosphopeptide analysis indicated several changes in the specific 32P labeling pattern, with altered phosphorylation occurring at both termini of the mutant protein compared with the wild-type T. Loss of p53 binding is therefore concomitant with changes in ATPase activity, oligomerization, stability, and in vivo phosphorylation of T and can be correlated with defective replication and restricted transformation functions. That so many biochemical changes are associated with a single substitution in the hydrophobic region of T is consistent with its importance in regulating higher-order structural and functional relationships in SV40 T.

Adenosine Triphosphatases↗
PubMed1988

Bulimia nervosa. Uncovering a secret disorder.

Bulimia nervosa is a common eating disorder among women. Sociocultural and interpersonal pressures are thought to be highly influential in the development of the syndrome. An association with depression has also been suggested. Recognizing bulimia nervosa is usually difficult, because patients are hesitant to reveal their symptoms. If the condition is diagnosed early in its course, the prognosis is more favorable. Use of tricyclic antidepressants and psychotherapy is the accepted treatment regimen.

Adolescent↗
PubMed1988

Characterization of simian virus 40 large T antigen by using different monoclonal antibodies: T-p53 complexes are preferentially ATPase active and adenylylated.

We used 21 monoclonal antibodies (PAbs 100 to 117, 405, 419, and KT3) specific for different determinants in simian virus 40 (SV40) large T antigen (T) and one antibody specific for p53 that coprecipitates T complexed with p53 (T-p53) to analyze T in SV40-infected CV1 cells. We measured the ATPase specific activity, extent of adenylylation, and p53 content of T precipitated by antibodies directed against the N-terminal region I (0.65 to 0.62 map units), the midregion III (0.43 to 0.28 map units) containing both the ATPase- and nucleotide-binding sites, and the C-terminal region IV (0.28 to 0.17 map units) of T. Lytic T appeared to exist in three different forms with respect to p53 binding and ATPase activity. The most ATPase-active form of T was that precipitated by PAb 122. This T-p53 complex contained only 6% of the total T but contributed 35% of the ATPase activity, on average. Free p53 isolated from 3T6, Ann-1, or L929 cells had no apparent ATPase activity. A second form of T precipitated by several antibodies had little associated p53 but appreciable ATPase activity, accounting for 15 to 20% of total T and 60 to 70% of the ATPase activity. The rest of T constituted the third form and was also depleted in p53 but had a decreased ATPase specific activity. Thus, the remaining 75 to 80% of T had 15 to 20% of the ATPase specific activity. Antibodies specific for region III precipitated T with both altered ATPase activity and altered amounts of bound p53. PAbs 104 and 114 reacted with ATPase-active T but inhibited ADP hydrolysis, suggesting that they were inactivating antibodies. T that was preferentially adenylylated in vitro corresponded to T that was also preferentially ATPase active. T bound to p53 was adenylylated to a higher specific activity than total T. In addition, p53 itself was significantly adenylylated under these conditions. The results suggest that ATPase activity and p53 binding are structurally and functionally related and that p53 alters biochemical activities of T and plays a role in productive infection.

Adenosine Triphosphatases↗
PubMed1987

Use of antipsychotic drugs in depression. Problems and opportunities.

Antipsychotic drugs have an important place in pharmacologic treatment of depression. Major depression with psychotic features responds poorly to treatment if an antipsychotic is not used in addition to an antidepressant; however, an antipsychotic confers no additional benefit in nonpsychotic depression. Antipsychotic drugs do have significant short- and long-term side effects, including pseudoparkinsonism, dystonia, akathisia, and tardive dyskinesia. The possibility of a good therapeutic response with minimal side effects can be increased if psychotic depression is diagnosed accurately and the antipsychotic is prescribed according to established clinical guidelines.

Antidepressive Agents, Tricyclic↗
PubMed1986

Free and viral chromosome-bound simian virus 40 T antigen: changes in reactivity of specific antigenic determinants during lytic infection.

Simian virus 40 (SV40) large T antigen (TAg), both free and bound to mature 70S and replicating 90S SV40 chromosomes, was prepared from lytically infected cells. The relative reactivity of the different TAg-containing fractions toward 10 monoclonal antibodies directed against three different regions in SV40 TAg and toward an antibody against the p53 protein was measured. The results for free TAg indicated that all of the determinants in both the amino-terminal (0.65 to 0.62 map units) and carboxy-terminal (0.28 to 0.17 map units) regions were highly reactive, whereas all five determinants located between 0.43 and 0.28 map units in the midregion of TAg were poorly reactive. For TAg bound to replicating chromosomes, all but one of the antibodies specific for TAg were highly reactive. Thus, antigenic sites in the middle of TAg, the region important for nucleotide binding and ATP hydrolysis (an activity required for viral DNA replication), were more accessible in TAg-replicating DNA complexes. As replicating molecules matured into 70S chromosomes, three or more determinants at different locations in TAg bound to chromatin became two- to fivefold less reactive, indicating other changes in TAg structure. Overall, at least nine different antigenic determinants in the TAg molecule were identified. Anti-p53 was reactive with about 10% of the free TAg and the same amount of SV40 chromosomes of all ages, suggesting that p53-TAg complexes are not preferentially associated with either replicating or mature viral chromosomes. When the reactivity of both mature and replicating labeled SV40 chromosomes with polyclonal tumor anti-T was measured as a function of time after purification, TAg bound to mature chromosomes appeared to dissociate about fourfold faster than that bound to replicating chromosomes. The relative amount of TAg in various subcellular fractions was measured by an enzyme-linked immunosorbent assay. Approximately 1.3% of the total TAg was estimated to be associated with SV40 chromosomes in infected cells. Based on the relative amounts of TAg and viral DNA in the 70S and 90S fractions, replicating chromosome-TAg complexes were estimated to bind 4.8 times more TAg per DNA molecule, on the average, than mature chromosome-TAg complexes. Together, these results are consistent with major differences in TAg structure when free and associated with replicating and nonreplicating SV40 chromosomes.

Animals↗
PubMed1985

Scrotal reconstruction following an avulsion injury.

Scrotal reconstruction following avulsion of the scrotal skin often is a time-consuming, multistage repair. We present an alternative method of repair using a subcutaneous soft tissue expander.

Accidents, Occupational↗
PubMed1983

Clovoxamine kinetics in an early clinical trial.

Elimination kinetics of the new antidepressant clovoxamine were determined in a preliminary clinical trial in 10 depressed patients. When final oral doses of 50 mg clovoxamine fumarate were given, the mean peak steady-state plasma concentration was about 60 ng/ml after 3 hr. Clovoxamine elimination proceeded by an apparent single-phasic, first-order decline with a mean t1/2 of 9.5 +/- 2.8 hr. One subject had an unusually long t1/2 (31.5 hr) and had correspondingly high clovoxamine plasma concentrations. The mean apparent volume of distribution (Vd) calculated from oral dosage was 19.5 +/- 6 l/kg, but one atypical subject had an apparent Vd of 96 l/kg. The mean apparent oral clearance was 25.5 +/- 12.5 ml/min/kg. These parameters should be of assistance in planning dosage regimens and monitoring therapeutic blood levels according to kinetic principles. Atypical clovoxamine kinetics can be associated with abnormally high or low blood levels and could therefore lead to variability in clinical response.

Adult↗
PubMed1983

Hepatic enzyme induction patterns and phenothiazine side effects.

D-Glucaric acid excretion was followed in psychotic patients treated with phenothiazines for 12 days and in a control group of subjects who had no psychiatric disease. About half the psychiatric patients had a treatment-related rise in D-glucaric acid excretion compatible with enzyme induction. These patients had fewer and less severe neurologic side effects than those who did not have a significant rise in urinary D-glucaric acid levels. It is concluded that individual differences in metabolism of phenothiazines may in part account for the variability in clinical response to these drugs.

Adolescent↗
PubMed1983

Cognitive therapy of depression: theory and practice.

Cognitive therapy is based on the premise that cognition, the process of acquiring knowledge and forming beliefs, is a primary determinant of mood and behavior. After reviewing the basic theories of cognitive therapy, the authors discuss its application to the treatment of depression. They theorize that cognitive therapy can improve depressive mood and behavior by focusing on the depressed patient's cognitive disorder. This disorder includes impaired learning and memory function and a systematic negative bias in thinking. The authors note the encouraging results of preliminary outcome studies of this new treatment of depression; such results, they conclude, warrant further development and testing of cognitive therapy.

Adaptation, Psychological↗