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F Palmer

Publications and source records attributed to F Palmer.

10 recordsLinked to original sources
PubMed2000

Messenger RNAs located in myelin sheath assembly sites.

The targeting of mRNAs to specific subcellular locations is believed to facilitate the rapid and selective incorporation of their protein products into complexes that may include membrane organelles. In oligodendrocytes, mRNAs that encode myelin basic protein (MBP) and select myelin-associated oligodendrocytic basic proteins (MOBPs) locate in myelin sheath assembly sites (MSAS). To identify additional mRNAs located in MSAS, we used a combination of subcellular fractionation and suppression subtractive hybridization. More than 50% of the 1,080 cDNAs that were analyzed were derived from MBP or MOBP mRNAs, confirming that the method selected mRNAs enriched in MSAS. Of 90 other cDNAs identified, most represent one or more mRNAs enriched in rat brain myelin. Five cDNAs, which encode known proteins, were characterized for mRNA size(s), enrichment in myelin, and tissue and developmental expression patterns. Two of these, peptidylarginine deiminase and ferritin heavy chain, have recognized roles in myelination. The corresponding mRNAs were of different sizes than the previously identified mRNA, and they had tissue and development expression patterns that were indistinguishable from those of MBP mRNA. Three other cDNAs recognize mRNAs whose proteins (SH3p13, KIF1A, and dynein light intermediate chain) are involved in membrane biogenesis. Although enriched in myelin, the tissue and developmental distribution patterns of these mRNAs differed from those of MBP mRNA. Six other cDNAs, which did not share significant sequence homology to known mRNAs, were also examined. The corresponding mRNAs were highly enriched in myelin, and four had tissue and developmental distribution patterns indistinguishable from those of MBP mRNA. These studies demonstrate that MSAS contain a diverse population of mRNAs, whose locally synthesized proteins are placed to contribute to myelin sheath assembly and maintenance. Characterization of these mRNAs and proteins will help provide a comprehensive picture of myelin sheath assembly.

Animals↗
PubMed1992

Monitoring electron spin by running geonium atom as microaccelerator.

Following the classic work of McMillan and of Bohm and Foldy, we have developed a phase equation describing the microsynchrocyclotron acceleration process in geonium. By computer integration of this equation, we are able to confirm that, by making use of the slight relativistic spin dependence of the zero-energy cyclotron frequencies, the acceleration process can be made selective enough to distinguish between spin-up and spin-down states. Quantum effects have been allowed for approximately.

Journal Article↗
PubMed1992

Practical zero-shift tuning in geonium.

Compositeness of the electron may show up in a very small deviation of the measured electron g factor from one calculated for a point electron by quantum electrodynamics. The precision of our g measurements is currently limited by an interaction of the cyclotron motion with standing waves in the trap cavity containing the electron. The important element introduced here is the systematic exploration of the trap cavity modes and the electron's coupling to them by measuring the shifted electron g factor gc = gc(omega e) as a function of the cyclotron frequency omega e. By measuring gc values at five different omega e values and modeling the trap cavity by six lumped LC circuits, the L values for the four most important modes may be determined and finally the unshifted g value may be extracted. Auxiliary experiments are relied upon only for the L values of the two least critical cavity modes. By designing the trap as a high-Q microwave cavity, an electron cyclotron and anomaly resonance linewidth one or even two orders of magnitude narrower than in free space may be approached without introducing appreciable frequency shifts.

Journal Article↗
PubMed1991

Geonium "K" experiment using spin dependency of cyclotron frequency supports g data of earlier geonium "S" work.

By substituting the relativistic spin state dependence of the cyclotron frequency for the continuous Stern-Gerlach effect and running the geonium atom as a microsynchrocyclotron accelerator we have detected spin flips of the individual trapped electron. In our initial efforts we have been able to obtain a simple symmetric spin resonance about 4-fold narrower instead of a complex asymmetric one and also to support but not as yet seriously test the result of the earlier geonium "S" work, g/2 = 1. 001 159 652 185 5(40).

Journal Article↗
PubMed1975

Differential diagnosis of hypercalcemia by the chloride/phosphate ratio.

The serum chloride and phosphate levels were measured and the chloride/phosphate ratios calculated in a group of eighty-four hypercalcemic patients. Although patients with hyperparathyroidism frequently had phosphate levels in the low normal range (less than 3 mg/100 ml) and chloride levels in the nigh normal range (greater than 102 mEq/L), they were nevertheless significantly different from the groups of patients with nonparathyroid hypercalcemia in whom phosphate levels were usually higher (greater than 3 mg/100 ml) and chloride levels usually lower (less than 102 mEq/L). The chloride/phosphate ratio was higher than 33 in 94 per cent of hyperparathyroid patients and lower than 33 in 96 per cent of other hypercalcemic patients. Thus, the measurements of serum phosphate and chloride levels and the calculation of the chloride/phosphate ratios were useful diagnostic screening tests that discriminated between patients with hypercalcemia of parathyroid and nonparathyroid origin with an accuracy of 95 per cent.

Bicarbonates↗