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D Cross

Publications and source records attributed to D Cross.

At least 73 records · Page 4Linked to original sources
PubMed1991

Subjective probability and delay.

Human subjects indicated their preference between a hypothetical $1,000 reward available with various probabilities or delays and a certain reward of variable amount available immediately. The function relating the amount of the certain-immediate reward subjectively equivalent to the delayed $1,000 reward had the same general shape (hyperbolic) as the function found by Mazur (1987) to describe pigeons' delay discounting. The function relating the certain-immediate amount of money subjectively equivalent to the probabilistic $1,000 reward was also hyperbolic, provided that the stated probability was transformed to odds against winning. In a second experiment, when human subjects chose between a delayed $1,000 reward and a probabilistic $1,000 reward, delay was proportional to the same odds-against transformation of the probability to which it was subjectively equivalent.

Adult↗
PubMed1990

Transforming growth factor beta 1 has differential effects on B cell proliferation and activation antigen expression.

There is accumulating evidence that TGF beta 1 is an important immunoregulatory molecule. Here we report evidence that TGF beta 1 has potent effects on murine B cells. It is profoundly inhibitory to the proliferation of quiescent B cells activated in model systems using both thymus-independent and thymus-dependent stimuli and arrests cells predominantly at the G1 cell-cycle stage. It also blocks the proliferation of B cell blasts, with a similar accumulation at stage G1. In parallel with this antiproliferative effect, TGF beta 1 inhibits induction of the expression of a series of "activation Ag" including transferrin receptor, RL388, and Ly-6, in mitogen-stimulated B cells. It also inhibits the induction of Ly-6 expression by IL-4, a nonmitogenic stimulus. In contrast to these negative influences, TGF beta 1 induces modestly increased expression of MHC class II Ag in quiescent B cells, and more marked increases in both B cell blasts and mitogen-stimulated cells. We speculate that in the appropriate context TGF beta 1 may be a cytokine that promotes productive B cell-Th cell interaction.

Animals↗
PubMed1990

Mouse chimeras and genetic rescue of mosaic muscle.

The nuclear-cytoplasmic relationships existing within mosaic muscle will likely determine whether myoblast transfer can effectively rescue diseased muscle. The mouse chimera preparation is one source of such mosaic muscle in which that in vivo relationship can be investigated in the complete absence of complicating immunological or surgical trauma. For several metabolic enzymes, the mature muscle fiber appears to contain a homogeneous mix of the proteins encoded by multiple myonuclei. This relationship is clearly not representative of all muscle proteins, as several examples of proteins highly localized to "nuclear territories" have now been described. Nonetheless, the intrafiber distribution of certain enzymes, particularly GP1-1, is appropriate for the basis of a genotype marking system applicable to mosaic fibers. In vitro rescue of mdg myotubes is readily achievable by incorporation of few normal myonuclei and possibly by only one. In vivo requirements are apparently far more stringent and an hypothesis in which the mdg gene product, a Ca+(+) channel subunit, is restricted to nuclear territories would be consistent with the disparate results obtained in vitro and in vivo. Finally, chimeras containing mdx/mdx cells may show a partial amelioration of muscle pathology and may provide a means of determining the minimum genetically normal myonuclear compliment required to prevent degeneration of dystrophin-deficient fibers.

Animals↗
PubMed1989

Definition of the HLA-Aw43 antigen.

The HLA antigen Aw43 has been observed only in Southern African populations. In order to confirm its identity and clarify its definition, ten cells with this specificity were shipped to laboratories in England, the United States of America and Australia to be tested with the sera from the 10th International Histocompatibility Workshop. The results of tests on nine of these cells which were sufficiently viable indicated that HLA-Aw43 is a distinct serological specificity which could be distinguished from both the A10 cross-reacting group (A25, A26 and Aw34) and A29. The Aw43 specificity segregated in two South African Negro families, and occurred commonly in association with Bw70. The occurrence of HLA-Aw43 in South African Caucasoids, in contrast to its absence in other Caucasoid groups, is probably due to genetic admixture with indigenous South African populations.

Black People↗
PubMed1988

Expression of size-selected messenger RNA encoding the brain and adrenal gland angiotensin-II receptor in Xenopus laevis oocytes.

The expression of the rat angiotensin-II receptor has been studied in Xenopus oocytes. Poly(A)+ RNA isolated from the brain and adrenal gland was injected into oocytes, and the expression of the receptor in the oocyte plasma membrane was assayed by measuring the change in membrane potential in the presence of angiotensin-II. Expression of the angiotensin-II receptor was detected 1.0-1.5 days after messenger RNA (mRNA) injection, and the degree of membrane depolarization was proportional to the amount of mRNA injected. Ca+2 channel blockers inhibited the angiotensin-II-induced depolarization. The total mRNA was fractionated by preparative agarose gel electrophoresis and each fraction was assayed for its ability to induce angiotensin-II depolarization. The mRNA encoding the angiotensin-II receptor was found in a single fraction of 4.4 kilobases.

Adrenal Glands↗
PubMed1987

Nasopharyngeal carcinoma, aplastic anemia, and various malignancies in a family: possible role of Epstein-Barr virus.

We report on a family ascertained because of sibs affected with nasopharyngeal carcinoma. Other relatives had aplastic anemia or other malignancies and most were born of consanguineous parents. Epstein-Barr virus has been strongly implicated in the pathogenesis of nasopharyngeal carcinoma. It has also been suggested as a cause of aplastic anemia and other neoplasms. We postulate that this extensive German-Mennonite family has a heritable defect in the immune response to Epstein-Barr virus making its members at excessive risk for a number of different malignancies. This immunologic predisposition may be HLA associated and appears to be inherited as an autosomal recessive trait.

Adolescent↗
PubMed1987

Synthesis and expression of functional angiotensin II receptors in Xenopus oocytes injected with rat brain mRNA.

Xenopus laevis oocytes were injected with poly(A)+ mRNA isolated from rat brain and superfused in a medium containing either serotonin, angiotensin II or bradykinin. Applications of serotonin or angiotensin II to injected oocytes elicited, in a dose-dependent manner, changes in membrane potential. The angiotensin II receptor was desensitized fairly rapidly in the continued presence of the agonist. No response was obtained with bradykinin. The selectivity of the angiotensin II-induced response was demonstrated by the finding that the angiotensin II antagonist [( Sar1,Ala8]angiotensin II, saralasin) blocked the angiotensin II-induced response. It is concluded that an appropriate fraction of brain mRNA is capable of directing the synthesis and correct insertion of functional angiotensin II receptors in the Xenopus oocyte membrane.

Angiotensin II↗
PubMed1987

Probability and delay in commitment.

In the first stage of a two-stage choice, human subjects chose between probabilistic access to a second choice (between a small high-probability reward and a large low-probability reward) and commitment to the large low-probability reward. When confronted with the second-stage choice, subjects strongly preferred the small high-probability reward. When the first-stage probability (of access to the second stage) was high, subjects strongly preferred the path leading to the choice in the second stage. But when the first-stage probability was low, subjects committed themselves to the large low-probability reward. These results parallel those obtained by Rachlin and Green (1972) with pigeons and constitute some evidence that probabilities may be interpreted as delays.

Journal Article↗
PubMed1987

Infant search and object permanence: a meta-analysis of the A-not-B error.

Research on Piaget's stage 4 object concept has failed to reveal a clear or consistent pattern of results. Piaget found that 8-12-month-old infants would make perserverative errors; his explanation for this phenomenon was that the infant's concept of the object was contextually dependent on his or her actions. Some studies designed to test Piaget's explanation have replicated Piaget's basic finding, yet many have found no preference for the A location or the B location or an actual preference for the B location. More recently, researchers have attempted to uncover the causes for these results concerning the A-not-B error. Again, however, different studies have yielded different results, and qualitative reviews have failed to yield a consistent explanation for the results of the individual studies. This state of affairs suggests that the phenomenon may simply be too complex to be captured by individual studies varying 1 factor at a time and by reviews based on similar qualitative considerations. Therefore, the current investigation undertook a meta-analysis, a synthesis capturing the quantitative information across the now sizable number of studies. We entered several important factors into the meta-analysis, including the effects of age, the number of A trials, the length of delay between hiding and search, the number of locations, the distances between locations, and the distinctive visual properties of the hiding arrays. Of these, the analysis consistently indicated that age, delay, and number of hiding locations strongly influence infants' search. The pattern of specific findings also yielded new information about infant search. A general characterization of the results is that, at every age, both above-chance and below-chance performance was observed. That is, at each age at least 1 combination of delay and number of locations yielded above-chance A-not-B errors or significant perseverative search. At the same time, at each age at least 1 alternative combination of delay and number of locations yielded below-chance errors and significant above-chance correct performance, that is, significantly accurate search. These 2 findings, appropriately elaborated, allow us to evaluate all extant theories of stage 4 infant search. When this is done, all these extant accounts prove to be incorrect. That is, they are incommensurate with one aspect or another of the pooled findings in the meta-analysis. Therefore, we end by proposing a new account that is consistent with the entire data set.

Attention↗
PubMed1984

Disease expression in +-/+- ----mdg/mdg mouse chimeras: evidence for an extramuscular component in the pathogenesis of both dysgenic abnormal diaphragm innervation and skeletal muscle 16 S acetylcholinesterase deficiency.

Homozygous mdg/mdg mice die at birth and express a syndrome of abnormalities, the most striking of which is a gross failure of skeletal muscle development. Recently, additional abnormalities in the development of nerve-muscle relationships have been recognized; in particular, on muscle fibers within the diaphragm, motor end plates are inappropriately dispersed and, in all muscles, there is a paucity of the 16 S form of acetylcholinesterase (AChE). These abnormalities could result entirely as secondary consequences of the primary muscle defect or from expression of the mdg defect in additional cell types, e.g., motor neurons. To determine if the muscle genotype alone is responsible for these defects in dysgenic mice, chimeras composed of both dysgenic and normal cells have been investigated. Different glucosephosphate isomerase variants existed in the mdg/mdg and normal cells comprising these chimeras and the mutant, normal, or mosaic genotypes of chimera diaphragm and skeletal muscle was estimated by measuring the relative proportions of each isozyme. In two chimeras, the diaphragm innervation pattern was revealed by AChE cytochemistry and in both, discrete regions of abnormally dispersed and normally restricted motor end-plate zones were observed. No correlation between these patterns of innervation and the assessed genotype of the muscle fibers existing in each area was observed. The relative 16 S AChE content in the limbs of four chimeras was found to range from 2.5 to 42.0%. Here also, no correlation between 16 S AChE content and the muscle genotype was observed. The results of these investigations are not consistent with a model of mdg/mdg pathogenesis in which only the skeletal muscle is primarily affected; an extramuscular deficiency responsible for at least part of the full mdg/mdg syndrome is therefore suggested.

Acetylcholinesterase↗
PubMed1977

Autoantibodies to an altered IgG in human breast cancer.

Recent studies have shown that antibody in the serum of patients with carcinoma of the breast reacts with two distinct antigens obtained from breast cancer tissue. Hence, there are two antibodies. The first antibody reacts against the Fc fragment of immunoglobulin and is also found in the sera of patients with benign breast disease and certain inflammatory lesions and, therefore, does not seem to have any significant meaning for the patient with carcinoma of the breast. The second antibody is directed against the Fab fragment of human immunoglobulin that is found in breast cancer tissue. Recent experiments have shown that in immunodiffusion tests, this autoantibody reacts not with normal IgG(Fab), but rather with heat-aggregated Ig(Fab). It is thought that tumor-associated antibodies react with antigens on the tumor cell surface. Intracellular enzymes then proceed to fragment the attached antibody, leaving the Fab fragments attached on the cell surface. With intact immunosurveillance, the host appreciates this altered immunoglobulin (Fab). It is suggested that the autoantibody then formed against this fragment reacts with the fragment attached to the tumor cell, thereby allowing the tumor cell to be destroyed. Clinical data supporting this hypothesis are derived from the fact that 9 patients having this autoantibody to the Fab fragment are alive at 1 year after their carcinoma of the breast.

Adenofibroma↗
PubMed1975

Percutaneous renal biopsy with localization by retrograde pyelography.

We describe the use of retrograde pyelography for renal localization during percutaneous biopsy in 6 patients. Since we have had no major complications with this procedure and have obtained adequate tissue in all cases we conclude that this method of localization for renal biopsy is the procedure of choice in the severely uremic patient.

Adult↗