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Biomedical subjects

D E Nelson

Publications and source records attributed to D E Nelson.

At least 91 records · Page 5Linked to original sources
PubMed1989

Immunocytochemical localization of serotonergic fibers innervating the ocular circadian system of Aplysia.

The isolated eye of the mollusc, Aplysia californica, contains a circadian pacemaker whose phase can be regulated by serotonin. The results of previous biochemical and physiological studies indicate that serotonin is used as a transmitter of circadian information in the eye. Although the effects of serotonin on various physiological processes in the Aplysia eye have been studied, very little is known about the anatomy of the serotonergic innervation. We have examined the innervation of the eye using immunocytochemical methods. Serotonin-immunoreactive processes were observed in the optic nerve, in the accessory optic nerves, in the connective tissue capsule surrounding the eye, and within the eye itself. There appeared to be two sources of serotonergic input to the eye of Aplysia. One set of immunoreactive fibers was contained in the optic nerve and entered the eye in the neuropil region before radiating outward towards the peripheral retina in the layer below the photoreceptor cell bodies. A second serotonin-immunoreactive input to the eye entered from the accessory optic nerves and these fibers formed a dense plexus of fibers in the connective tissue capsule surrounding the eye. Serotonin-immunoreactive fibers from the plexus penetrated the eye and appeared to terminate in the peripheral portion of the retina. No serotonin-immunoreactive cell bodies were observed in the eye, nerves, or connective tissue capsule. These results support the hypothesis that serotonergic fibers innervate the retina of Aplysia and that these fibers travel through two distinct anatomical pathways: the optic nerve and the accessory optic nerves.

Animals↗
PubMed1989

Molecular Cloning of Osmotin and Regulation of Its Expression by ABA and Adaptation to Low Water Potential.

In response to adaptation to NaCl, cultured tobacco cells (Nicotiana tabacum L. cv Wisconsin 38) synthesize a major 26 kilodalton protein which has been named osmotin due to its induction by low water potentials. To help characterize the expression of osmotin in adapted cells, a cDNA clone for osmotin has been isolated. Abscisic acid induces messenger RNA encoding osmotin. Levels of this mRNA in adapted cells are approximately 15-fold higher than in unadapted cells. Message for osmotin is present at constant levels through the growth cycle of adapted cells, while in unadapted cells, the level decreases during exponential phase of growth and increases again when the cells approach stationary phase. While abscisic acid induces the message for osmotin, a low water potential environment appears to be required for accumulation of the protein. An osmotic shock to unadapted cells does not increase the amount of message or protein present most likely because this treatment does not induce immediately the accumulation of abscisic acid. The increased expression of osmotin in adapted cells is not correlated with an increase in osmotin gene copy number. Osmotin is homologous to a 24 kilodalton NaCl-induced protein in tomato, as well as thaumatin, maize alpha-amylase/trypsin inhibitor and a tobacco mosaic virus-induced pathogenesis-related protein.

Journal Article↗
PubMed1988

A practical approach to workers' compensation.

An understanding of workers' compensation and of the physician's role in it can significantly improve communication with patients, insurance companies and employers. Early rehabilitation is essential. Treatment of difficult patients can be enhanced by recognizing and treating the factors that are delaying recovery, encouraging activity and minimizing the use of narcotics. Factors delaying recovery include depression, alcoholism and pending litigation against the employer.

Accidents, Occupational↗
PubMed1987

Occupation and industry data obtained from death certificates: the effect and influence of case selection.

This study first examined the accuracy of death certificate diagnoses of 4,954 cases of cancer of the lung, liver, nasopharynx, and pleura/peritoneum, then compared usual occupation and industry based on case selection from the Metropolitan Detroit Cancer Surveillance System (MDCSS), a population-based cancer registry, with cases selected from death certificates for the above types of tumors to examine the effect of misclassification. Accuracy of death certificate cancer diagnoses ranged from 93.4% for lung cancer to 28.6% for malignancies of the pleura/peritoneum. The mix of usual occupation/industry titles obtained from death certificate cases and MDCSS cases was similar for lung cancer but not for malignancies of the pleura/peritoneum (35.7% of cases from the registry v 11.1% from death certificates for the automobile industry, P = .05). The effect of misclassification and utility of usual occupation/industry statements on death certificates is discussed.

Death Certificates↗
PubMed1984

Pharmacokinetics of sulfamethazine in male, female and castrated male swine.

The concentration of sulfamethazine in plasma and sulfamethazine and its metabolites in urine were compared in male, female and castrated male swine. A surgical technique for placement of catheters in the urinary bladder was used to facilitate the collection of urine in males and castrated males. The elimination rate of sulfamethazine from plasma and the excretion of parent drug and metabolites into urine did not differ significantly among females, males and castrated male swine.

Animals↗
PubMed1981

Effect of timolol maleate on intraocular pressure and pupil cycle time in normal eyes.

One drop of 0.5% timolol maleate instilled into the normal eyes of four subjects produced a marked reduction of intraocular pressure that was maximal at 3 hours but not significant after 12 hours. Instillation of one drop a day for 30 days produced a reliable, maintained reduction of intraocular pressure in the treated eye. The pupil cycle time in both eyes was measured at least twice daily for 1 week before timolol treatment to assess the reproducibility of the test and then twice daily for the 30 days of treatment with timolol. The drug had no significant effect on the pupil cycle time. Measuring the pupil cycle time should afford the ophthalmologist a useful method of assessing the progress of glaucomatous damage to the optic nerve while the patient is undergoing treatment with timolol, an assessment that was not possible when patients were treated with pilocarpine.

Administration, Topical↗
PubMedDate not supplied

Predictors of tobacco sales to minors.

BACKGROUND: Our purpose was to determine which characteristics of buyers, stores, and store clerks predicted successful tobacco sales to minors. METHODS: Seventeen minors visited randomly selected retail outlets in the Austin, Texas, area and attempted to purchase tobacco products. We used logistic regression modeling to determine independent predictors of successful purchase attempts. RESULTS: Overall, 101 of 165 attempts (61.2%) were successful. Although legally required, only 25.3% of stores posted warning signs about underage purchase of tobacco, and stores with signs were no less likely to sell to minors than stores without signs. Successful attempts were more common from vendors in metropolitan locations and from vendors with no alcohol products. Only 8.1% of attempts succeeded when buyers were questioned (usually about age), compared with 95.6% of attempts when no questions were asked (P < 0.001). The best predictor of a successful purchase attempt was failure to question buyers (adjusted odds ratio = 1,850; P < 0.001). CONCLUSIONS: Warning signs had no effect on vendors' compliance with the state minors' access law, and failure to question minors about their age substantially increased the odds of a successful purchase. Laws prohibiting tobacco sales to minors should be enforced by requiring vendors to obtain proof of buyers' ages for persons who appear to be < 30 years of age.

Adolescent↗
PubMedDate not supplied

Pipe smoking in the United States, 1965-1991: prevalence and attributable mortality.

BACKGROUND: National pipe-smoking prevalence data have rarely been reported, and mortality associated with pipe smoking has not been estimated. METHODS: We analyzed National Health Interview Survey data from 1965, 1966, 1970, 1987, and 1991 to estimate adult pipe-smoking prevalence in the United States. For each of these years, we estimated pipe smoking-attributable mortality from chronic obstructive pulmonary disease and cancers of the oral cavity, larynx, esophagus, and lung. RESULTS: From 1965 to 1991, the prevalence of current pipe smoking for men declined 12.1 percentage points (from 14.1% to 2.0%) while pipe smoking remained very uncommon among women. By 1991, pipe smoking was a behavior found primarily among men age 45 years or older. Most men who smoked pipes also used other tobacco products, especially cigarettes. About 830 deaths (range 720-2,495) in 1965 and 1,095 deaths (range 655-2,820) in 1991 were attributable to pipe smoking. CONCLUSIONS: If current trends continue, pipe smoking will become extremely rare in the United States by the year 2000. Reasons for the decline in pipe smoking may include the lack of appeal of pipe smoking to women and adolescents or the increasingly unfavorable image of smoking behavior in general. Prevention and cessation efforts need to be directed against all forms of tobacco, including smokeless tobacco use, cigar smoking, and pipe smoking.

Adult↗