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D Cross

Publications and source records attributed to D Cross.

70 records · Page 4Linked to original sources
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

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↗
PubMedDate not supplied

A simplified method for quality control of deglycerolized erythrocytes.

Quality control to detect inadequately deglycerolized red blood cells can be easily and inexpensively accomplished by suspending the deglycerolized cells in either recipient serum or normal saline in the same way in which the routine crossmatch is performed. In vitro hemolysis is readily and consistently apparent when the residual glycerol exceeds either 2.4% (in saline) or 2.5% (in serum). In contrast to generally held beliefs, the in vivo 24-hour survival of red blood cells with a residual glycerol concentration of up to 2.7% was demonstrated to be 76% of greater, a level which is well above what is usually accepted as adequate.

Blood Transfusion↗
PubMedDate not supplied

Extended hospitalization of medically stable children dependent on technology: a focus on mutable family factors.

This study identified three factors that influenced extended hospital stay in medically stable children dependent on medical technology. A retrospective review of 50 charts in a level II nursery was conducted. Bivariate analysis identified factors contributing to extended stay: parental factors, societal factors, health care factors, and presence of disease. Multiple regression explained 98% of the variance in extended length of stay. Family factors accounted for 19.6%, nonfamily factors accounted for 42.5%, and the two sets of factors together accounted for an additional 35.9%. Family-related issues with a high potential for change were identified. Pediatric providers should develop family intervention strategies that identify the most appropriate level of care that both advocates in the best interest of the child and family and contains the rising cost of health care.

Analysis of Variance↗
PubMedDate not supplied

Meta-analysis of theory-of-mind development: the truth about false belief.

Research on theory of mind increasingly encompasses apparently contradictory findings. In particular, in initial studies, older preschoolers consistently passed false-belief tasks-a so-called "definitive" test of mental-state understanding-whereas younger children systematically erred. More recent studies, however, have found evidence of false-belief understanding in 3-year-olds or have demonstrated conditions that improve children's performance. A meta-analysis was conducted (N = 178 separate studies) to address the empirical inconsistencies and theoretical controversies. When organized into a systematic set of factors that vary across studies, false-belief results cluster systematically with the exception of only a few outliers. A combined model that included age, country of origin, and four task factors (e.g., whether the task objects were transformed in order to deceive the protagonist or not) yielded a multiple R of .74 and an R2 of .55; thus, the model accounts for 55% of the variance in false-belief performance. Moreover, false-belief performance showed a consistent developmental pattern, even across various countries and various task manipulations: preschoolers went from below-chance performance to above-chance performance. The findings are inconsistent with early competence proposals that claim that developmental changes are due to tasks artifacts, and thus disappear in simpler, revised false-belief tasks; and are, instead, consistent with theoretical accounts that propose that understanding of belief, and, relatedly, understanding of mind, exhibit genuine conceptual change in the preschool years.

Child↗
PubMedDate not supplied

Theory of mind and conceptual change.

We agree with the commentaries by Scholl and Leslie, and also by Moses, that the meta-analytic findings do not definitively rule out early competence accounts. But they do make extant versions of such accounts increasingly unlikely. In particular, the meta-analytic findings argue against executive function expression accounts, including the Theory-of-Mind Mechanism/Selection Processor account advocated by Scholl and Leslie. Specifically, Scholl and Leslie articulate two explicit predictions of their account: that task manipulations that attenuate inhibitory demands should differentially advantage older children, and that theory-of-mind developments should occur with consistent timetables. Both of these specific predictions are clearly contradicted, not supported, by the meta-analytic findings.

Child↗