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J Blank

Publications and source records attributed to J Blank.

At least 19 recordsLinked to original sources
PubMed1998

Mailing strategies and costs of recruiting heavy smokers in CARET, a large chemoprevention trial.

Recruitment costs represent a major portion of the budget for large clinical trials during the initial years of the study. Further, the rate of recruitment affects allocation of resources in future years. To learn about the costs and yields of recruiting from different populations and under different mailing strategies, we monitored recruitment yields of eligible heavy smokers for the Carotene and Retinol Efficacy Trial (CARET) at the Portland Study Center. Yields from the mailings, measured by response rate, percent of potential participants randomized, and related costs per randomization varied both by mailing strategy and by population targeted. Yield and cost varied significantly across population sources. Less variation was observed among various mailing strategies. Tracking the recruitment process yield provided useful information that allowed us to adjust recruitment approaches and achieve our randomization goals quickly and economically.

Aged↗
PubMed1996

Elongation factor Ts from Thermus thermophilus-- overproduction in Escherichia coli, quaternary structure and interaction with elongation factor Tu.

The gene encoding the elongation factor Ts from Thermus thermophilus was sequenced, cloned and the protein overproduced in Escherichia coli. In comparison to the EF-Ts from E. coli with 282 amino acid residues, EF-Ts from T. thermophilus is considerably shorter, differing by 86 amino acids. EF-Ts from the thermophile is stable at high temperatures, which facilitates its separation from E. coli proteins. Purified T. thermophilus EF-Ts forms a homodimer with a disulfide bridge between the two cysteine residues at position 190. The modification of Cys19O by iodoacetamide affects neither the dimerization nor the ability of EF-Ts to facilitate the nucleotide exchange of elongation factor Tu. The disulfide bridge was detected only in purified EF-TS, but not in protein extracts immediately after cell disruption. The physiological role of this disulfide bridge remains, therefore, unclear. Besides the quaternary (EF-TU . EF-Ts)2 complex, a ternary EF-TU . EF-Ts2 complex was detected by gel permeation chromatography and polyacrylamide gel electrophoresis. Trypsin cleavage after Lys48 or modification of Cys78 yield inactive EF-Ts, that does not bind to EF-Tu but is still capable of forming homodimers.

Amino Acid Sequence↗
PubMed1995

Overexpression and purification of Thermus thermophilus elongation factors G, Tu, and Ts from Escherichia coli.

The translation elongation factors G (EF-G), Tu (EF-Tu), and Ts (EF-Ts) from the extreme thermophilic bacterium Thermus thermophilus were overproduced in Escherichia coli. The fus gene coding for EF-G and the tufA gene coding for EF-Tu were expressed under the control of a tac promoter, whereas EF-Ts was overproduced with the T7 RNA polymerase system. A detailed description for the purification of the three elongation factors from E. coli is presented. EF-G and EF-Tu are isolated by Q-Sepharose FF chromatography, heat treatment at 65 or 60 degrees C, respectively, and Sephacryl S200 gel permeation chromatography. For the purification of EF-Ts, a heat denaturation step is followed by DEAE-cellulose chromatography and a cation exchange EMD-SO-3 650 column. The overproduced factors show the same properties as those purified from T. thermophilus. As the crystal structures of T. thermophilus EF-Tu and EF-G have been solved recently, many questions concerning the function of particular residues or domains arise, which may be best addressed by studying the in vitro behavior and structure of altered recombinant constructs. The methods presented here should facilitate such studies.

Bacteriophage T7↗
PubMed1993

Depletion of olfactory bulb norepinephrine by 6-OHDA disrupts chemical cue but not social recognition responses in male rats.

In the present experiment, 6-OHDA was infused directly into the olfactory bulb (OB) to produce a localized neurotoxic lesion. Habituation/dishabituation behavioral tests were then conducted to measure recognition responses to chemical cues (urine as a stimulus) and to social stimuli (ovariectomized rat as a stimulus). Infusion of 6-OHDA resulted in a near complete depletion of OB-norepinephrine (NE), whereas it had little effect (15% reduction) on OB dopamine (DA) contents. Nor were any significant effects on hypothalamic, hippocampal, olfactory tubercle, and corpus striatal NE and DA contents observed. Behaviorally, dishabituation responses to chemical cues were greatly impaired, however, there was relatively little effect on social behavior dishabituation responses. These results demonstrate that 6-OHDA can be used to produce a near complete but localized depletion of OB-NE. This treatment impairs dishabituation responses to chemical cues but not social stimuli indicating that OB-NE appears necessary for processing of chemical cue, but not social memory recognition process.

Animals↗
PubMed1993

Selection for active E. coli tRNA(Phe) variants from a randomized library using two proteins.

In vitro selection was used to isolate active Escherichia coli tRNA(Phe) variants from randomized libraries. Functional tRNAs were first selected by multiple rounds of binding to Escherichia coli phenylalanyl-tRNA synthetase. These variants were then aminoacylated and selected for affinity to elongation factor-Tu. By randomizing potential recognition nucleotides, the importance of residues U20, G34, A35, A36 and U59, previously identified to be required for specific recognition by E. coli phenylalanyl-tRNA synthetase (FRS), was confirmed. However, the sequences of several active variants imply that the wild-type tertiary interactions G10-C25-U45 and A26-G44 are not required for recognition, as previously suggested. Selection of functional tRNAs from a second library randomized at positions normally involved in conserved tertiary interactions revealed new combinations of nucleotides at these positions, suggesting the presence of novel tertiary interactions. In both libraries, active sequences containing deletions were isolated. Taken together, it is clear that FRS is active with substrates having an unexpectedly broad sequence diversity. Finally, the potency of this method is illustrated by the identification of a second class of variants that was isolated by virtue of the presence of an impurity in the FRS preparation.

Base Sequence↗
PubMed1992

Relaxation therapy reduces anxiety in child and adolescent psychiatric patients.

The immediate effects of relaxation therapy (RT) were assessed in 40 hospitalized children and adolescents with diagnoses of adjustment disorder and depression. These effects were assessed using a within subjects pre-test/post-test design and by comparison with a control group of 20 depressed and adjustment disorder patients who watched a 1-h relaxing videotape. The 1-h RT class consisted of yoga exercise, a brief massage and progressive muscle relaxation. Decreases were noted in both self-reported anxiety and in anxious behavior and fidgeting as well as increases in positive affect in the RT but not the video group. In addition, adjustment disorder patients and a third of the depressed patients showed decreases in cortisol levels following RT, while no changes were noted in the video group. Thus, both diagnostic groups appeared to benefit from the RT class.

Adjustment Disorders↗
PubMed1988

Nitrogen-dioxide-induced emphysema in rats. Lack of worsening by beta-aminopropionitrile treatment.

We evaluated the effect of beta-aminopropionitrile (beta APN) on the nitrogen dioxide (NO2) animal model of emphysema. Rats maintained on a beta APN-supplemented or a regular diet were exposed to 30 ppm NO2 for intervals ranging from 1 to 8 wk. Emphysema development was assessed by histologic evaluation and by changes in lung volume and mean linear intercept values. Evidence of pathologic changes were also documented by clinical and radiographic findings of osteolathyrism. The induction of centriacinar emphysema was attributed specifically to NO2 exposure. Neither the severity of the emphysema nor the time course of its development was altered by the beta APN-supplemented diet. These findings are in marked contrast to those observed with the exogenous elastase model of the disease, and they suggest that elastin synthesis and repair may not modulate elastin destruction in the NO2 model of emphysema.

Aminopropionitrile↗
PubMed1987

Neutrophil recruitment and degranulation during induction of emphysema in the rat by nitrogen dioxide.

Rats exposed to 30 ppm NO2 continuously for 3 to 6 wk developed mild centriacinar air-space enlargement and mild interstitial fibrosis. The emphysematous changes did not become more severe after 6 wk with continued NO2 exposure for as long as 14 additional weeks. Elastase inhibitory capacity (EIC) and the total protein concentration increased acutely in lung lavage fluid, consistent with the histologic evidence of pulmonary edema, then subsided but remained above control levels for the entire exposure period. The ratio of EIC to total protein remained unchanged relative to that in control animals. Neutrophils accumulated in the lung and were recoverable by lavage with the same relative concentration profile as observed for total protein. The average elastase activity per neutrophil in cells recovered from the air space by lung lavage was 60% less than in cells recovered from peripheral blood. This was true for control or NO2-exposed rats. Thus, emphysematous changes in the NO2-exposed rat were accompanied by a marked neutrophil recruitment concomitant with an increased neutrophil elastase burden in the lung, which may have directly contributed to lesion development.

Animals↗
PubMed1986

Transplantation of HLA-haploidentical T-cell-depleted marrow for leukemia: autologous marrow recovery with specific immune sensitization to donor antigens.

Autologous marrow recovery without engraftment of donor marrow was observed after bone marrow transplantation (BMT) for two patients with acute lymphoblastic leukemia. Each had received marrow from a haploidentical mixed lymphocyte culture (MLC) reactive donor after pretransplant conditioning with total body irradiation and high-dose cyclophosphamide. To minimize graft-vs-host disease, the marrow was depleted of T cells in vitro by treatment with a monoclonal anti-T-cell antibody and complement. Two weeks after each transplant, reactive lymphocytes were noted transiently in the blood of each patient. Analysis of karyotype, HLA type, and in vitro MLC responsiveness proved the lymphocytes to be of host, not donor, origin. MLC studies showed rapid proliferative responses specifically to stimulating cells from the BMT donor, indicating in vivo sensitization to donor antigens. Return of hematopoietic function was markedly delayed, but it eventually normalized after several months, without evidence of chimerism. These studies confirm that some immune and hematopoietic stem cells of host origin survive the high-dose chemoradiotherapy used as transplant conditioning. Because these immune cells are specifically reactive to donor alloantigens, more potent suppression of host immunity may be needed to prevent nonengraftment of T-cell-depleted, HLA-mismatched bone marrow.

Adult↗
PubMed1985

Relapse of host leukemic lymphoblasts following engraftment by an HLA-mismatched marrow transplant: mechanisms of escape from the "graft versus leukemia" effect.

Leukemic relapses and graft versus host disease (GvHD) remain major complications following allogeneic bone marrow transplantation for leukemia. We present clinical and laboratory details for an eight-year-old boy who received a T-cell-depleted HLA-mismatched marrow transplant as therapy for acute lymphoblastic leukemia (ALL) in second remission. Engraftment with donor marrow was prompt and without any acute GvHD. Nevertheless, the patient's original ALL recurred and proved fatal. The patient remained a chimera with persistent donor lymphocytes present at the time of posttransplant relapse and subsequent to treatment with unsuccessful reinduction chemotherapy. In vitro immune studies showed that these leukemic cells could be recognized and destroyed by the donor's lymphocytes. The relapse itself suggests, however, that the donor's lymphocytes did not effectively destroy the patient's histoincompatible ALL cells in vivo following establishment of the chimeric state. Potential mechanisms are presented to account for this presumed "escape" from the postulated "graft versus leukemia" effect.

Acute Disease↗
PubMed1985

Suppressed expression of blood group B antigen and blood group galactosyltransferase in a preleukemic subject.

The B antigen activity was severely diminished in a patient's RBCs at the preleukemic stage prior to chemo- or radiotherapy. The amount of H sites of the patient's RBC membranes was found to be comparable to that of O RBC membranes. The activity of alpha (1----2) fucosyltransferase (H enzyme) was not severely decreased in the patient's plasma and bone marrow. However, the activity of alpha (1----3) galactosyltransferase (B enzyme), which converts H substance to B substance, was drastically reduced in the patient's bone marrow. Thus, the diminished B antigen in the patient's RBCs was caused mainly by the blockage of conversion of the H substance to B substance. It is suggested that the viral oncogene linked to the ABO locus at q34 of chromosome No. 9 would occasionally suppress the expression of blood group A and B enzymes and A and B antigens.

ABO Blood-Group System↗
PubMed1984

Blood component transfusion in the intensive care nursery. Indications and special problems.

Increasingly, transfusions of component blood products are used in the setting of the neonatal intensive care unit. There is a need to analyze the indications and potential complications of this therapy critically. We review here the problems primarily unique to the neonatal population and suggest an approach to the transfusion requirements of this group. Specifically, we discuss the rationale, indications and complications of red cell, granulocyte, and platelet transfusions in these patients. Discussion of exchange transfusion and the particular blood banking requirements of these patients will be reviewed in subsequent articles.

Blood Transfusion↗