Biomedical subjects
Publications and source records attributed to S J Moss.
Saliva may be considered as being similar to enamel but in a liquid phase. Saliva, the mechanics of remineralization and demineralization, the acquired pellicle and the enamel surface all act to maintain the status quo, resisting mineral loss from the enamel.
Subunit-specific DNA probes for the chicken muscle acetylcholine receptor have been used in conjunction with Northern blots and dot-blots based upon the SP6/T7 RNA polymerase reaction to quantitate changes in the steady-state mRNA levels of all four subunits during development. In pectoral muscle, maximal subunit transcript levels are observed at day 12 in ovo for alpha, days 12-16 in ovo for beta, day 14 in ovo for gamma, and days 12-14 in ovo for delta. Interestingly, two delta-subunit transcripts which have somewhat different patterns of temporal expression are detected. At the peak of expression of each subunit mRNA the absolute levels of the alpha-, beta-, and gamma-subunit transcripts are very similar (49.2, 66.0, and 70.7 attomoles of transcript/micrograms of poly(A)+ RNA, respectively) whereas that for the summed delta-subunit transcripts is significantly lower (17.8 attomoles/micrograms of poly(A)+ RNA). Further, this lower level of delta-subunit mRNA is observed from day 10 to day 16 of embryonic development. We conclude that subunit transcript availability is important in the synthesis of acetylcholine receptor protein during development and that the level of the delta-subunit transcript can be rate limiting in the expression of this receptor.
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The effects of osmotic stress on corneal endothelium were investigated by exposing rabbit corneas to anisosmotic conditions, and then perfusing the corneas with isosmotic glutathione bicarbonate Ringer solution for 4 hr at 35 degrees C. During the perfusion, endothelial function was assessed by measuring corneal thickness with a specular microscope. After perfusion, the corneas were prepared for scanning and transmission electron microscopy. Endothelial ultrastructure and function were well maintained after exposure to a wide range of osmolality (0.12-2.7 osmol/kg), but this tolerance of osmotic stress was dependent both on the duration and the temperature of exposure to the anisosmotic conditions. Exposure to an osmolality of 2.7 osmol/kg for 15 min at 23 or 37 degrees C resulted in gross damage to the endothelium when the hyperosmotic agent was sodium chloride. This damage was not the result of increased osmolality per se nor cellular shrinkage because the endothelium tolerated exposure to a sucrose solution of the same osmolality for 15 min at 37 degrees C. The detrimental effect of sodium chloride, however, was mitigated by reducing the temperature of exposure to 0 degrees C or reducing the duration of exposure to 5 min. These results suggest that endothelial cells become more tolerant of high electrolyte concentrations with reducing temperature, and this could be an important factor in the survival of the endothelium in corneal cryopreservation. The results also help to define the limits of osmotic shrinkage and swelling tolerated by endothelial cells. This will be of value in overcoming the detrimental osmotic effects associated with the addition and, in particular, the removal of cryoprotectants.
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Dental caries is the most prevalent disease among young people in the United States today. Yet, most parents don't realize that early dental care is the best insurance against adult dental disease. Because prevention should begin at birth, long before the first dental visit, nurse practitioners can play an important role in educating parents about the need for early attention to their children's dental health. This article presents to the nurse practitioner an overview of preventive dental techniques, including the effectiveness and application of fluorides, the value of early and regular oral cleaning habits and the importance of early and regular consultations with health care professionals.
We have studied the mRNAs encoding all four subunits of the acetylcholine receptor in 13-day embryonic, innervated and denervated chicken pectoral muscle. In all three states the transcript sizes of the alpha, beta-, gamma- and delta-subunit mRNAs were approximately 3.2, 2.8, 1.8 and 1.9 kb respectively. Denervation was found to result in a large increase in the steady-state levels of each mRNA compared with those in innervated muscle. This increase was 8- to 9-fold for the beta and delta subunits and approximately 12-fold for the alpha subunit. The evidence obtained shows a coordinate regulation of the acetylcholine receptor genes in response to denervation. Interestingly, no gamma-subunit transcript was detected in innervated muscle, while significant levels were detected in embryonic and denervated tissue. This evidence suggests that there exists in a non-mammalian muscle acetylcholine receptor an additional subunit, analogous to the bovine epsilon subunit, and shows that the extra-junctional receptor of adult denervated muscle is produced by the same set of mRNAs which produce the major form of the receptor in embryonic muscle.
The Xenopus oocyte is the only system currently available for the full expression of mRNAS encoding membrane receptors and ion channels. Its application in the case of brain mRNAs for the GABAA receptor is illustrated, including the production of receptor subunits and its chloride channel with characteristic pharmacology.
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