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Biomedical subjects

D North

Publications and source records attributed to D North.

36 records · Page 2Linked to original sources
PubMed1982

Cell-type specific codon usage and differentiation.

This paper presents evidence derived from the selective use of codons in ca. 40 eukaryotic genes (or messages derived from them) that codon usage is one of the most conserved features of messages for specific cell products. The theory has been developed by several investigations that the kinds of products of many if not most kinds of differentiated cells is determined by the pattern of translation abilities each cell possesses as it differentiates. A correllary of this thesis is that the groups of code words used for products of specific cell types, INDEPENDENTLY OF THE SPECIES INVOLVED, should exclude specific kinds of code words in one cell type and not another. To test this thesis, the specific frequency of codon usage and non-usage has been collated from the recently published literature and subjected to appropriate computer analysis. We find that: (1) certain codons are not used at all in any message for globins; (2) the pattern of codon usage is characteristic of specific products from specific embryonic derivatives, e.g. erythrocytes; (3) that certain code words are discriminated against generally in nearly all vertebrate cell messages evaluated; and (4) that the cell type from which a message is derived can be identified, at least in the case of 9 globin messages derived from species separated by millions of generations, purely on the basis of codon usage. From these studies it can be inferred that some evolutionary factor prevents the use of "forbidden" code words in specific kinds of cells. We propose that this factor derives from the fact that a "silent" mutation to a code word which is untranslatable by a differentiated cell will be lethal in the homozygous condition and that the thesis that so-called "codon restriction" is an important determinative factor in limiting what differentiating cells can synthesize in many kinds of developing cells explains the available evidence more adequately than alternative theories.

Animals↗
PubMed1978

Modification by suppressor cells and serum factors of the cell-mediated immune response in experimental pyelonephritis.

A marked suppression of the thymusderived (T)-lymphocyte response to concanavalin A has been demonstrated in vitro during renal infection. Suppression of the T-lymphocyte response in vitro was seen as early as 2 h after the induction of renal infection, but maximum suppression was found 24-72 h later. A population of suppressor cells in the splenic lymphocyte population, generated during the host's response to infection, contributed to the depressed lymphocyte response. Removal of suppressor cells restored the mitogenic responsiveness of the remaining splenic lymphocytes. Conversely, in co-culture experiments, a suppressor cell present in the splenic lymphocyte population of pyelonephritic animals was shown to be capable of suppressing the mitogenic responsiveness of normal splenic lymphocytes. Significantly reduced host vs. graft responses by the pyelonephritic animals confirmed, in vivo, the depression of cell-mediated immune mechanisms. An additional suppressive factor was found in the serum of pyelonephritic animals which depressed in vitro the mitogenic responsiveness of splenic lymphocytes from normal animals. Support for the suppressive role of this serum factor was found when splenic lymphocytes from pyelonephritic animals were tested in vivo in the absence of homolgous serum (graft vs. host). Under these conditions, the lymphocytes showed an enhanced reaction compared with lymphocytes from normal animals. The presence of a suppressor cell population and a serum factor, both capable of depressing cell-mediated mechanisms, may be major factors contributing to the establishment of infection in the kidney.

Animals↗
PubMed1976

A case of twin chimerism.

A case of twin chimerism is presented and shown by cytogenetic studies, red cell grouping, and white cell HL-A typing. The sex of each twin is confirmed by examination of buccal smears and their chimeric state is confirmed by non-reactivity in the mixed lymphocyte culture system. The results of these investigations are discussed.

Chimera↗
PubMed1975

Acquiescent renal infection.

The relationship between bacterial infection of the renal parenchyma with Escherichia coli and the establishment of pathologic lesions has been investigate experimentally. Infection was established in one kidney and the bacteriologic, pathologic and immunologic features of infection were compared in the pyelonephritic and contralateral unmanipulated kidney. Whereas active bacterial infection was associated with pathologic changes in the pyelonephritic kidney, a poor correlation was found between bacterial growth and the gross pathology and histopathologic changes in the contralateral kidney. The conclusion from these studies is that infection of the kidney is not always associated with pathologic changes. The term "acquiescent infection" has been used to describe this host-parasite relationship in which active, persistent, bacterial infection is not associated with pathologic lesions. Evidence is presented that bacteria in the contralateral unmanipulated kidney are present in the renal parenchyma and that bacterial proliferation can be induced following renal trauma. Activation of infection and bacterial proliferation did not always result in histopathologic damage to the kidney and was not associated with an increase in serum antibody.

Animals↗
PubMedDate not supplied

Acupressure wrist bands to relieve nausea and vomiting in hospice patients: do they work?

This study assessed the effects of acupressure wrist bands on the nausea and vomiting of terminally ill patients. Using a single subject experimental design, six hospice patients were exposed to three conditions: An acupressure wrist band; A placebo wrist band; A no wrist band condition. Patients and their caregivers rated nausea and vomiting during the treatment. Despite some difficulty obtaining complete data, the results of this preliminary test indicate that acupressure wrist bands were not effective in reducing nausea and vomiting in this small sample of hospice patients.

Acupuncture Points↗