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Biomedical subjects

R Epstein

Publications and source records attributed to R Epstein.

At least 109 records · Page 6Linked to original sources
PubMed1985

Animal cognition as the praxist views it.

The distinction between psychology and praxics provides a clear answer to the question of animal cognition. As Griffin and others have noted, the kinds of behavioral phenomena that lead psychologists to speak of cognition in humans are also observed in nonhuman animals, and therefore those who are convinced of the legitimacy of psychology should not hesitate to speak of and to attempt to study animal cognition. The behavior of organisms is also a legitimate subject matter, and praxics, the study of behavior, has led to significant advances in our understanding of the kinds of behaviors that lead psychologists to speak of cognition. Praxics is a biological science; the attempt by students of behavior to appropriate psychology has been misguided. Generativity theory is an example of a formal theory of behavior that has proved useful both in the engineering of intelligent performances in nonhuman animals and in the prediction of intelligent performances in humans.

Animals↗
PubMed1985

Amount consumed varies as a function of feeder design.

Studies of pigeon behavior in which magazine-cycle duration is varied suggest that many researchers assume that feeders of different designs dispense food at roughly the same rate. However, Epstein (1981) showed that, with a commonly used feeder, the amount of grain a pigeon consumes is a negatively accelerated function of magazine-cycle duration. The present experiment shows that, with a different commonly used feeder, amount consumed is roughly a linear function of magazine-cycle duration. At a duration of 60 seconds, the second feeder dispenses roughly 10 times as much food as the first. Thus, reports of studies in which magazine-cycle duration is varied should identify the design of the feeder employed, and in some cases, authors should consider determining the feeding functions for those feeders.

Animal Feed↗
PubMed1984

Linkage of the Igl-1 structural and regulatory genes to Akv-2 on chromosome 16.

Evidence is presented here for a close linkage between Akv-2, an ecotropic provirus found uniquely on chromosome 16 of AKR/N mice, and the immunoglobulin lambda 1 light chain locus, Igl-1. No recombinants between the Igl-1 locus and Akv-2 were found by Southern blot analysis of DNA obtained from progeny of the backcross of (AKR/N X SJL/J)F1 to SJL/J, indicating that these genes map within 5.9 cM of each other. A probe specific for the flanking sequence of Akv-2 was used to detect the provirus, while one specific for the Igl-1 constant region was used to determine which allele of the structural gene was expressed in the backcross mice. The constant region of Igl-1 differs between AKR/N and SJL/J with respect to a site for the restriction endonuclease KpnI. This backcross was also used to seek recombinants between the regulatory, Igl-1r, and structural, Igl-1, loci of the immunoglobulin light chain locus, since the existence of such recombinants would prove that these loci are distinct. Since only parental types were recovered in the offspring, the structural and regulatory loci are no more than 2.3 cM apart, and the implications of this finding are discussed.

Animals↗
PubMed1984

An effect of immediate reinforcement and delayed punishment, with possible implications for self-control.

Behavior said to show self-control occurs virtually always as an alternative to behavior that produces conflicting consequences. One class of such consequences, immediate reinforcement and delayed punishment, is especially pervasive. Three experiments are described in which an effect of immediate reinforcement and delayed punishment is demonstrated. The results suggest that when immediate reinforcement and delayed punishment are imminent, the reinforcer alone controls the organism's behavior (in other words the organism behaves "impulsively"). The key to self-control, therefore, may be the acquisition of a large number of avoidance behaviors relevant to reinforcers that are correlated with delayed punishment. Human self-control may indeed involve such a process but undoubtedly involves others as well.

Animals↗
PubMed1983

Fate of cloned bacteriophage T4 DNA after phage T4 infection of clone-bearing cells.

Plasmid pBR322 replication is inhibited after bacteriophage T4 infection. If no T4 DNA had been cloned into this plasmid vector, the kinetics of inhibition are similar to those observed for the inhibition of Escherichia coli chromosomal DNA. However, if T4 DNA has been cloned into pBR322, plasmid DNA synthesis is initially inhibited but then resumes approximately at the time that phage DNA replication begins. The T4 insert-dependent synthesis of pBR322 DNA is not observed if the infecting phage are deleted for the T4 DNA cloned in the plasmid. Thus, this T4 homology-dependent synthesis of plasmid DNA probably reflects recombination between plasmids and infecting phage genomes. However, this recombination-dependent synthesis of pBR322 DNA does not require the T4 gene 46 product, which is essential for T4 generalized recombination. The effect of T4 infection on the degradation of plasmid DNA is also examined. Plasmid DNA degradation, like E. coli chromosomal DNA degradation, occurs in wild-type and denB mutant infections. However, neither plasmid or chromosomal degradation can be detected in denA mutant infections by the method of DNA--DNA hybridization on nitrocellulose filters.

Cloning, Molecular↗
PubMed1983

Recombination between bacteriophage T4 and plasmid pBR322 molecules containing cloned T4 DNA.

Reciprocal recombination between T4 DNA cloned in plasmid pBR322 and homologous sequences in bacteriophage T4 genomes leads to integration of complete plasmid molecules into phage genomes. Indirect evidence of this integration comes from two kinds of experiments. Packaging of pBR322 DNA into mature phage particles can be detected by a DNA--DNA hybridization assay only when a T4 restriction fragment is cloned in the plasmid. The density of the pBR322 DNA synthesized after phage infection is also consistent with integration of plasmid vector DNA into vegetative phage genomes. Direct evidence of plasmid integration into phage genomes in the region of DNA homology comes from genetic and biochemical analysis of cytosine-containing DNA isolated from mature phage particles. Agarose gel electrophoresis of restriction endonuclease-digested DNA, followed by Southern blot analysis with nick-translated probes, shows that entire plasmid molecules become integrated into phage genomes in the region of T4 DNA homology. In addition, this analysis shows that genomes containing multiple copies of complete plasmid molecules are also formed. Among phage particles containing at least one integrated copy, the average number of integrated plasmid molecules is almost ten. A cloning experiment done with restricted DNA confirms these conclusions and illustrates a method for walking along the T4 genome.

Cloning, Molecular↗
PubMed1983

Induction of lambda 1-immunoglobulin is determined by a regulatory gene (r lambda 1) linked (or identical) to the structural (c lambda 1) gene.

The cis-acting gene regulating specifically the inducibility of lambda 1-bearing B cells has been mapped within 2.9 cM of the structural gene. If the lambda 1lo-phenotype is due to the gly leads to val interchange in C lambda 1, then an argument can be made that (a) the lambda 1lo-phenotype is due to inefficient induction of lambda 1lo-bearing B cells and (b) B cell triggering is dependent upon a conformational change in the Ig receptor upon interaction with antigen. If the lambda 1lo-phenotype is due to a regulatory sequence linked to the structural C lambda 1-gene, then it must control the expression of the lambda 1-locus during development into adulthood, e.g., by an effect on methylation.

Animals↗
PubMed1983

Functional voice disorders. A review of 109 patients.

The records of 109 patients, presenting with functional voice disorder during the years 1977-1981, have been reviewed. The mean age was 45 years and the F : M ratio is 2 : 1. Excess voice use was not obviously an aetiological factor. Sixty-one of the 109 patients (56 per cent) were cured by speech therapy, in that their voices returned to their pre-morbid state, and a further 28 (26 per cent) were improved by therapy; seven patients (6 per cent) did not improve and 13 (12 per cent) were lost to follow-up. Of the patients that were 'cured', 54 per cent were discharged after three months' treatment and 72 per cent after six months' treatment. Eight per cent required treatment for more than a year.

Adolescent↗
PubMed1983

Effect of whole-body hyperthermia on cell survival, metastasis frequency, and host immunity in moderately and weakly immunogenic murine tumors.

The effects of whole-body hyperthermia (WBH) on animal tumors and on metastasis frequency were studied. The tumors were a chemically-induced fibrosarcoma, FSa-I, which is moderately immunogenic and a spontaneously arisen fibrosarcoma, FSa-II, which is very weakly immunogenic. The WBH was given at 42.5 degrees in an incubator which had an auxiliary heater for accurate temperature control. Animal core temperature reached 41.5 degrees in 30 min. The lung colony assay revealed that the WBH for 60 min given at 24 hr after i.v. injection of single cells gave no lethal damage to either FSa-I or -II tumor cells. A significant inhibition of tumor growth was found when large tumors were given three daily WBH treatments. The frequency of lung metastasis was enhanced when large weakly immunogenic FSa-II tumors were treated by WBH, although no increase in the frequency was observed for FSa-I tumors of any size. Local hyperthermia did not significantly increase the metastasis rate of both tumors. These results suggest that the WBH might be useful for a treatment of large immunogenic tumors. However, the WBH is not a choice of treatment for possible micro-metastases.

Animals↗
PubMed1982

The fine structure of human rectal epithelium in acute graft-versus-host disease.

We compared the fine structure of the biopsied rectal mucosa of seven allogeneic bone marrow transplant recipients who had gastrointestinal graft-versus-host disease (GVHD) with that of four recipients without GVHD. In GVHD, lymphocytes formed the predominant cellular infiltrate. Lymphocytes indented the cytoplasmic membranes of enterocytes by point contact, extended broad pseudopods to the nuclear membranes of the enterocytes, and surrounded desmosomes. The membranes of target cells were never breached, however. We hypothesize that these lymphocyte-to-epithelial-cell contacts represent the recognition phase of alloimmune T-lymphocyte cytolysis. Damage to the enterocytes resulted in both coagulative necrosis and "apoptosis" (the development of membrane-bound cell fragments--"apoptotic bodies"). Epithelial injury and lymphocytic infiltration predominated in the bases of the crypts in mild GVHD and extended to the surface epithelium in severe GVHD. Chemoradiotherapy-induced injury, present early post-transplant, was diffuse and severe but transient. In GVHD, damage to the enterocytes, necrosis, and intercellular edema extended beyond the time of resolution of chemoradiotherapy-induced injuries. Patients without GVHD, studied after resolution of chemoradiation injury, had rectal epithelium with little or no injury and no evidence of either increased numbers of lymphocytes or of the intimate lymphocyte-to-epithelial-cell contacts described in those with GVHD.

Anemia, Aplastic↗
PubMed1981

In vivo expression of the rII region of bacteriophage T4 present in chimeric plasmids.

The expression of the T4 rII genes in uninfected cells has been examined by use of recombinant plasmids. Hybridization analysis of pulse-labelled RNA prepared from cells carrying pTB101, a plasmid that contains the end of T4 gene 60 and the beginning of gene rIIA, shows that about 0.7% of the labelled RNA is rII specific. By contrast, only 0.02% of pulse-labelled RNA prepared from cells carrying plasmid pTB301, which probably contains the middle-mode rIB promoter, may be rII specific. When separated strands of T4 DNA were used for hybridization, we found that the pTB101 transcripts have a strand specificity identical to that of the rIIA transcripts made during phage infection. The same strand specificity was observed irrespective of the orientation of the inserted DNA in the vector. This result argues that the transcripts initiate within the inserted DNA rather than somewhere else on the plasmid. We also found that essentially none of the pulse-labelled pTB101 RNA would hybridize to the DNA of a T4 deletion mutant that lacks the rIIA gene. This suggests that little of the gene 60 DNA of the plasmid is being transcribed. In addition to the rII transcript, a new protein of 56,000 Daltons molecular weight is found in cells carrying pTB101. Fingerprint analysis of the protein shows that it is specified by the rIIA gene of the plasmid. Taken together, these results indicate that transcription of the plasmid rIIA gene initiates at or near the beginning of the gene.

DNA, Viral↗