Biomedical subjects
Publications and source records attributed to D L Wilson.
Scalzi and Wilson use consensus research as a basis for determining content for graduate programs in nursing administration. They ask, what do practicing nurse executives do on the job? One hundred and eighty-four nurse executives from acute care, home care, long-term care, and occupational health rated and ranked their job functions.
The field of infant perceptual development has relied heavily on the preferential-looking and habituation paradigms. Despite the obvious advantages of employing standardized methodologies, there is a need to study how perceptual variables give rise to and guide action beginning in the neonatal period. It is argued here that, in the first 5 months of life, it is important to distinguish reflexive patterns of movement from voluntary and cortically controlled patterns. Some criteria are defined. This paper describes three experiments which utilized movement counters to record developmental changes in the frequency and synchrony of limb movements in infants under 5 months. The results show that there is a general increase in frequency of limb movements from 1 to 5 months, but with a plateau or even a decrease in activity from the middle of the third month to the end of the fourth month. It was also demonstrated that synchrony scores (co-activation) for pairs of limbs showed significant increases from 1 month to 5 months. Finally, in all three experiments the presentation of an attractive toy resulted in suppression of activity. The results of the three experiments are interpreted to measure a gradual increase in cortically controlled movement patterns.
1. The fungus C. bainieri, incubated for 7 days with methoxyphenamine alone or in combination with either sparteine or quinidine, gave N-desmethylmethoxyphenamine and its N-acetyl conjugate as major metabolites, while O-desmethylmethoxyphenamine, 5-hydroxymethoxyphenamine and 2-hydroxyamphetamine were produced in lesser amounts. In addition, 1-(2-hydroxyphenyl)-2-aminopropane, 1-hydroxy-1-(2-methoxyphenyl)-2-propanone, beta-hydroxymethoxyphenamine, and 1-(5-hydroxy-2-methoxyphenyl)-2-aminopropane were tentatively identified as minor components of the fungal biotransformation of methoxyphenamine. 2. As observed in mammalian systems, the addition of either sparteine or quinidine decreased the rate and extent of methoxyphenamine biotransformation. 3. C. bainieri may be a useful model for drug interaction studies.
Eight different methods of fluorographic enhancement of sensitivity to 35S decay after gel electrophoresis were compared. Using Kodak X-Omat AR X-ray film, we found that some fluors were about equivalent to 2,5-diphenyloxazole/dimethyl sulfoxide embedding, whereas several other fluors were not quite as effective, but still were significantly more sensitive than control autoradiography. The most sensitive procedures can yield a detectable darkening of film with less than 1 dpm/mm2 of 35S after a 1-week exposure.
The following two points are made in this article: (1) the likely existence of more than one underlying cause of senescence strengthens the case for the development of a number of reliable markers of aging and (2) the concept of a single biological or functional age for an organism should be used with great caution, if at all.
We have shown that bullfrog sciatic nerves respond to a conditioning lesion similarly to goldfish optic nerve and rat or mouse sciatic nerve; that is, following a crush the rate of regeneration is faster in nerves that have received a conditioning lesion compared to nerves that have not. Also, damaged nerve fibres show initial growth or sprouting earlier in a previously conditioned nerve compared to nerves that have not received a prior conditioning lesion. We have not detected changes in the transport of fast axonally transported proteins with the conditioning lesion paradigm, other than those changes seen in regenerating nerves after receiving a single lesion. However, more label was present in a few fast axonally transported proteins at the lesion site in conditioned nerves compared to non-conditioned nerves, and this difference is not apparently due to increased transport. It seems that changes in fast axonally transported proteins probably do not contribute directly to the mechanism underlying the conditioning lesion effect of higher out growth rates, although some of the fast transported proteins may be involved in functions, possibly at the growing tip of damaged fibres, which promote or result from the conditioning effect.
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Using two-dimensional polyacrylamide gel electrophoresis to analyze proteins, we have found subsets of periaxonal and fast-transported axoplasmic proteins that are released in vitro from regenerating sciatic nerve into a surrounding bath. Of the fast-transported proteins that are released from nerve, there is a subset of at least five polypeptides that appears in greater relative abundance in the bath than in the nerve. Some of these released, fast-transported proteins are glycosylated. Several periaxonally synthesized polypeptides are released in significantly greater amounts from regenerating nerve, and of these polypeptides, two are released in greater amounts from nerve only at regions of regeneration or distal to regeneration. These released polypeptides do not represent the most abundant of the locally synthesized proteins. The released, fast-transported and periaxonal proteins may play a role in intercellular signaling or in modulation of the extracellular environment during nerve regeneration.
Many characteristics of proteins that are fast axonally transported have been described, but the destinations of most within the neuron remain unknown. We have studied the destinations of some fast-transported proteins in sensory neurons of the bullfrog sciatic nerve, specifically to determine which may be deposited in axons and which may be destined for more distal, possibly terminal, areas. Dorsal root ganglia were pulse-labeled with [35S]methionine in vitro, following which they were separated from the sciatic nerve. After additional periods of transport, radioactive proteins from two areas of the nerve were separated by two-dimensional polyacrylamide gel electrophoresis and used to develop x-ray film. The first area contained the wavefront of transported radioactivity (wavefront region), whereas the second area was taken from nerve through which the wavefront had already passed (plateau region). The amount of radioactivity in certain fast-transported protein species from each area was determined by computer analysis of digitized video images of fluorographs. Certain proteins were preferentially left behind the wavefront and, therefore, may supply axon and possibly other nerve components, whereas other proteins were found almost exclusively in the wavefront and, hence, may supply more distal, possibly terminal, areas.
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The Therac 20 is an AECL medical linear accelerator that produces electron and photon beams. Electron fields are produced by a scanned beam; collimation is provided by two sets of primary collimators and further collimated by external electron trimmers located 11 cm above the plane of isocenter (100 cm). These collimators are not suitable for intracavitary treatment. To overcome this limitation, we have designed an intracavitary cone system that attaches to the electron trimmers. Since the trimmers do not have to be removed while this system is in use, there is no need to bypass the associated interlock system. The apparatus consists of a platform which slides onto the lower set of trimmers, onto which a lead insert is attached. Dosimetry measurements for 9, 13, and 17 MeV electron beams are reported for three different treatment cones.
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The phacoexcavator permits lens removal via the pars plana by mechanical disruption, hydration, and aspiration within the capsule. The instrument is suitable for use with unimanual, bimanual, or three-port methods. In five cases lenses estimated to have 2+ to 3+ nuclear sclerosis were removed successfully in less than three minutes. There were no postoperative complications and the only intraoperative complication was some loss of cortical material in one case. This was recovered and removed during the vitrectomy.
Radioactively labeled, fast-transported proteins were collected at ligatures placed on peripheral and central branches of spinal sensory nerves of the bullfrog. In agreement with previous studies, we found that the same species of proteins were transported down each branch. For each protein species analyzed we have measured the amount of radioactivity reaching each ligature, and calculated the ratio of radioactivity reaching the peripheral ligature to that reaching the central ligature. Not all protein species have the same ratio. This suggests that there may be differential transport of fast-transported proteins in axonal branches.
Tetrodotoxin (TTX)-sensitive Na currents were examined in single dissociated ventricular myocytes from neonatal rats. Single channel and whole cell currents were measured using the patch-clamp method. The channel density was calculated as 2/micron 2, which agreed with our usual finding of four channels per membrane patch. At 20 degrees C, the single channel conductance was 20 pS. The open time distributions were fit by a single-exponential function with a mean open time of approximately 1.0 ms at membrane potentials from -60 to -40 mV. Averaged single channel and whole cell currents were similar when scaled and showed both fast and slow rates of inactivation. The inactivation and activation gating shifted quickly to hyperpolarized potentials for channels in cell-attached as well as excised patches, whereas a much slower shift occurred in whole cells. Slowly inactivating currents were present in both whole cell and single channel current measurements at potentials as positive as -40 mV. In whole cell measurements, the potential range could be extended, and slow inactivation was present at potentials as positive as -10 mV. The curves relating steady state activation and inactivation to membrane potential had very little overlap, and slow inactivation occurred at potentials that were positive to the overlap. Slow inactivation is in this way distinguishable from the overlap or window current, and the slowly inactivating current may contribute to the plateau of the rat cardiac action potential. On rare occasions, a second set of Na channels having a smaller unit conductance and briefer duration was observed. However, a separate set of threshold channels, as described by Gilly and Armstrong (1984. Nature [Lond.]. 309:448), was not found. For the commonly observed Na channels, the number of openings in some samples far exceeded the number of channels per patch and the latencies to first opening or waiting times were not sufficiently dispersed to account for the slowly inactivating currents: the slow inactivation was produced by channel reopening. A general model was developed to predict the number of openings in each sample. Models in which the number of openings per sample was due to a dispersion of waiting times combined with a rapid transition from an open to an absorbing inactivated state were unsatisfactory and a model that was more consistent with the results was identified.
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