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Biomedical subjects

D L Wilson

Publications and source records attributed to D L Wilson.

At least 19 recordsLinked to original sources
PubMed1992

Compressed radiological images and workstation viewing.

The viewing of radiological images on workstations has peculiarities that must be taken into account in the design of a compression technique. The images may be manipulated on a workstation to change the contrast, to change the center of the brightness levels that are viewed, and even to invert the images. Because of the possible consequences of losing information in a medical application, bit-preserving compression is used for the images used for diagnosis. However, for archiving, the images may be compressed to 10% of their original size. A compression technique based on the discrete cosine transform takes the viewing factors into account by compressing the changes in the local brightness levels. The compression technique is a variation of the Consultive Committee on International Telephony and Telegraphy Joint Photograph Experts Group compression that suppresses the blocking of the discrete cosine transform except in areas of very high contrast.

Artifacts↗
PubMed1992

In vitro assessment of cytotoxicity and biotransformation of propranolol in Cunninghamella echinulata.

1. Biotransformation studies with five concentrations of racemic propranolol were conducted using the filamentous fungus Cunninghamella echinulata ATCC 9244. 2. The rate of formation and subsequent disappearance of a new major metabolite, 8-hydroxypropranolol, was dose-dependent. Desisopropylpropranolol and 4-hydroxypropranolol were also formed. 4-Hydroxypropranolol was the major fungal metabolite in earlier studies. 3. Propranolol exerted a dose-dependent response on biotransformation, fungal growth, dextrose utilization, ammonia formation and incubation broth pH. Determination of dextrose utilization and incubation broth pH would provide reliable, cost-effective and convenient alternative methods for cytotoxicological evaluation.

Ammonia↗
PubMed1992

Biotransformation of tri-substituted methoxyamphetamines by Cunninghamella echinulata.

1. Four trimethoxyamphetamine analogues were incubated with the filamentous fungus Cunninghamella echinulata. 2. 2,4,5-Trimethoxyamphetamine and 2,5-dimethoxy-4-ethoxyamphetamine were poorly metabolized by C. echinulata ATCC 9244 and C. echinulata var. elegans ATCC 9245. 2,5-Dimethoxy-4-(n)-propoxyamphetamine was mainly metabolized through N-acetylation and O-dealkylation with minor amounts of several aliphatic hydroxylation metabolites formed. 2,5-Dimethoxy-4-methylthioamphetamine was extensively metabolized to the corresponding sulphoxide. 3. 2,5-Dimethoxy-4-methylthioamphetamine metabolism was inhibited by ethanol and quinidine. Sparteine did not inhibit the formation of the sulphoxide and may have shunted the substrate through alternate metabolic pathways. 4. Incubation conditions can affect the rate and extent of fungal biotransformation of 2,5-dimethoxy-4-methylthioamphetamine, and influence dextrose utilization, ammonia formation and pH.

Amphetamines↗
PubMed1992

In vivo effects of interleukin-1 beta on blood leukocytes in BB rats prone or resistant to diabetes.

Previous studies have determined that daily low dose injections of the potent cytokine interleukin-1 beta (IL-1 beta) decreased the frequency of insulin-dependent diabetes mellitus (IDDM) in diabetes-prone (DP) BB rats. In contrast, high dose injections induced an earlier than normal onset. In this study we tested whether the effects of daily human recombinant IL-1 beta injections on leukocyte subsets were associated with its modulation of IDDM onset in BB rats. Prior to the onset of IDDM in DP BB rats, high dose IL-1 beta induced leukocytosis (P less than 0.05), neutrophilia (P less than 0.01), and monocytosis (P less than 0.001). At the onset of IDDM, lymphocyte (P less than 0.01) and neutrophil (P less than 0.001) numbers were increased in high dose treated DP rats but not in rats given saline or low dose IL-1 beta. In 60-day-old diabetes-resistant (DR) BB rats, neurophilia was induced by both low (P less than 0.05) and high (P less than 0.001) dose IL-1 beta without the development of IDDM. At 130 days of age, when the rats were killed, it was discovered that 14/22 (64%) IL-1 beta injected DR rats developed neutralizing IL-1 beta antibodies. Significantly lower neutrophil numbers were observed in high dose DR rats which developed IL-1 beta antibodies compared with those which did not (P = 0.032). Thus, neutrophilia was dissociated from high IL-1 beta acceleration of IDDM onset.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Summertime elevation of 222Rn levels in Huntsville, Alabama.

Indoor Rn concentrations and Rn in adjacent karst terrains were studied at four houses with crawlspaces in Huntsville, AL. In warm summertime weather, Rn-rich air may vent through limestone solution cavities exposed as holes at the surface of the properties. A probable interrelated-finding is that the indoor levels of 222Rn are distinctly higher in the summer than winter. The karst underlying the homes is structurally faulted and, in all probability, facilitates Rn transport from the solution cavities to the crawlspaces. Abrupt day-to-day changes in indoor Rn concentrations were recorded in addition to large seasonal changes. If the owners or residents of these particular homes had attempted to make, and interpret, short-term screening measurements for Rn during the fall season, problems, including false negatives, could have arisen because of order-of-magnitude changes in Rn concentration occurring over a few days. The best time of year to make screening measurements would be during the summer when indoor Rn concentrations are more likely to reach their maximum values.

Air Pollutants, Radioactive↗
PubMed1991

Alterations in cysteine proteinase content of rat lung associated with development of Pneumocystis carinii infection.

The rate of hydrolysis of three cysteine-type proteinase substrates, N-benzyloxycarbonyl-Arg-Arg-4-methyl-7-coumarylamide (AMC) (cathepsin B), Arg-AMC (cathepsin H), and N-benzyloxycarbonyl-Phe-Arg-AMC (cathepsin L), were determined in rat lung throughout the time course of the induction of Pneumocystis carinii infection by immunosuppression. Cathepsin B-like and cathepsin L-like activities fell below control values initially, but from week 8 of the immunosuppressive treatment significant increases above the control were noted. Cathepsin H-like activity was greater than control levels from week 3, and by week 12 it was 7,600% of the mean control value. When compared with the relative degree of infection, as assessed from the number of cysts present in lung impression smears, cathepsin B-like and cathepsin L-like activities were significantly increased only at heavy parasite burdens while cathepsin H-like activity displayed a close correlation with parasite number (r = 0.884; P less than 0.001). Activity was detected in lysates of purified P. carinii with all three substrates. Treatment of heavily infected animals with co-trimoxazole cleared the lungs of P. carinii, and this was accompanied by a marked reduction in proteinase activity, in particular, cathepsin H-like activity, which fell from 108- to 3-fold the mean control value following drug treatment. Analysis of cathepsin H isozyme patterns by fluorography following isoelectric focusing revealed differences between treated and control lung samples. In the immunosuppressed group, there was a time-dependent increase in the intensity of some of the bands observed in the controls and an appearance of several novel bands which corresponded to bands observed in lysates of P. carinii. It is likely, therefore, that the increased proteinase activity observed in the treated group is due, at least in part, to isozymes from P. carinii; consequently, cathepsin H-like activity might be of use diagnostically in the identification of P. carinii infection and in the estimation of parasite burden.

Animals↗
PubMed1991

Future preparation of occupational health nurse managers.

This article presents the results of a national survey of job activities of corporate level occupational health nurse managers. The survey was designed to identify the relative amount of time spent and importance attributed to specific areas of their current job. In general this sample tended to have more management experience and educational preparation than previously cited studies: over 50% had completed a graduate degree. The scores for importance and time spent were highly correlated. That is, occupational health corporate nurse managers seemed to allocate their time to job responsibilities they considered most important. Management activities related to policy, practice standards, quality assurance, staff development, and systems for client care delivery appear to represent the core responsibilities of occupational health nursing management. Curriculum recommendations for management positions in occupational health include: health policy, program planning, and evaluation; business strategy; applications of management information systems; quality assurance; and marketing.

Curriculum↗
PubMed1990

Impact of heating and air conditioning system operation and leakage on ventilation and intercompartment transport: studies in unoccupied and occupied Tennessee Valley homes.

Forced-air heating and air conditioning (HAC) systems caused an average and maximum increase in air infiltration rates of 1.8- and 4.3-fold, respectively, during brief whole-house studies of tracer gas decay in 39 occupied houses. An average increase in air infiltration rate of 0.33 +/- 0.37 h-1 corresponded to an incremental air leak of 240 m3/h, based on approximate house volume. More detailed tracer gas decay studies were performed in basement, kitchen and bedroom locations of six homes with low air infiltration rates (i.e., less than 0.25 h-1). The HAC mixed the indoor air efficiently between measurement sites. HAC operation also caused 1.1- to 3.6-fold increases in air infiltration rates, corresponding to absolute increases of 0.02 to 0.1 h-1. In an unoccupied research house, three-fold increases in average air infiltration rate with HAC operation (i.e., from 0.13 to 0.36 h-1) were reduced to two-fold (i.e., from 0.10 to 0.18 h-1) by sealing the external HAC unit and crawlspace ductwork system. This sealing also resulted in a 30 percent reduction in crawlspace-to-indoor transport rates with the HAC turned on. Blower door tests indicated a less than 20 percent reduction in house leakage area.

Air Conditioning↗
PubMed1990

Fungal metabolism of 4-substituted amphetamines.

1. rac.-4-Ethoxyamphetamine was incubated with 14 different yeast and fungal microorganisms. 4-Hydroxyamphetamine was the major metabolite; traces of N-acetyl-4-ethoxyamphetamine were also detected. 2. The major fungal (Cunninghamella) metabolite of 4-propoxyamphetamine and 4-benzyloxyamphetamine was 4-hydroxyamphetamine. The major metabolites of 4-methoxyamphetamine were N-acetyl-4-methoxyamphetamine and 4-hydroxyamphetamine. 3. Acetoin derivatives were formed when alkoxyamphetamine substrates were incubated in the presence of various fungi and yeasts. 4. The findings indicate that Cunninghamella echinulata may be a useful microbial model for drug disposition and interaction studies.

Amphetamines↗
PubMed1989

Patterns of movement in the first 6 months of life: new directions.

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.

Arousal↗
PubMed1989

Effect of sparteine and quinidine on the metabolism of methoxyphenamine by Cunninghamella bainieri.

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.

Biotransformation↗
PubMed1987

Effects of a conditioning lesion on bullfrog sciatic nerve regeneration: analysis of fast axonally transported proteins.

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.

Animals↗
PubMed1987

Subsets of axonally transported and periaxonal polypeptides are released from regenerating nerve.

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.

Animals↗
PubMed1985

Proteins in fast axonal transport are differentially transported in branches of sensory nerves.

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.

Animals↗
PubMed1985

Cardiac Na currents and the inactivating, reopening, and waiting properties of single cardiac Na channels.

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.

Animals↗