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Biomedical subjects

D Smyth

Publications and source records attributed to D Smyth.

13 recordsLinked to original sources
PubMed1992

Cocaine use, risk taking, and fatal Russian roulette.

OBJECTIVE: To examine the association between recent cocaine use and risk taking, particularly in the form of playing Russian roulette, a paradigm for extreme risk-taking behavior. DESIGN: A case-control study. CASES AND CONTROLS: The prevalence of cocaine use among all Russian roulette fatalities (N = 14) was compared with a demographically similar, randomly selected sample (N = 54) of all suicides by handgun during a contemporaneous 4-year period in New York City, NY. RESULTS: Recent use of cocaine, the most common drug found at autopsy, was detected in 64% of Russian roulette fatalities and in 35% of the control group (P less than .05). All Russian roulette fatalities were male and usually young and unemployed. Blacks and Hispanics accounted for 80% of all cases and were overrepresented compared with their numbers in the general population. CONCLUSION: In some populations cocaine may be associated with life-threatening risk-taking behaviors.

Adolescent↗
PubMed1991

Increased vasopressin immunoreactivity in the rat brain after a postmortem interval of 6 hours.

Enhanced immunocytochemical staining of vasopressin-containing neurons was observed after incubation of rat brain slices in Ringer medium for 6 h at room temperature, as compared to brain tissue fixed immediately after death. Hypothalamic vasopressin neurons in the supraoptic nucleus, the paraventricular nucleus and the suprachiasmatic nucleus stained more intensely after a postmortem interval of 6 h. Extrahypothalamic vasopressin neurons (VP) in the bed nucleus of the stria terminalis, the medial amygdala and the locus coeruleus proved to be stained as well. Extrahypothalamic VP neurons in the locus coeruleus could, until now, only be visualized after in vivo pretreatment with colchicine. In addition, staining was observed at two new sites, the dorsal raphe nucleus and the lateral septum. Staining of VP was corroborated by application of different antibodies directed against the intact vasopressin molecule as well as by antibodies directed against the other parts of the vasopressin precursor molecule, i.e. neurophysin and glycopeptide. The specificity of the VP-staining was validated by using pre-immune serum and using Brattleboro rat brain tissue, resulting in a negative staining in both cases. Furthermore, homogenated punches of the suprachiasmatic nucleus were submitted to iso-electric focussing on polyacrylamide gel, followed by press blotting and subsequent immunocytochemical staining for vasopressin. Iso-electric foccussing enabled us to characterize and quantify peptides in the suprachiasmatic nucleus. The vasopressin content increased 6 h postmortem, while c-terminal glycopeptide and neurophysin levels remained stable. Similar results were observed in the suprachiasmatic nucleus from decapitated rats whose brains were left intact in the skull for 6 h at room temperature.

Animals↗
PubMed1988

An unfortunate complication of self-therapy for seborrheic dermatitis.

The death of a young boy who practiced self-therapy of seborrheic dermatitis of the scalp is reported. Practitioners should be aware that peer pressure in today's teenage society, coupled with misinterpretation of therapeutic protocols, may result in the application of unorthodox treatment regimens.

Adolescent↗
PubMed1987

Vasopressin coexists in half of the corticotropin-releasing factor axons present in the external zone of the median eminence in normal rats.

Electron-microscopic immunocytochemistry of serial thin sections showed that, in normal rats, approximately 50% of corticotropin-releasing factor (CRF) axons in the external zone of the median eminence contained vasopressin (AVP) and AVP precursor-derived peptides coexistent in the same secretory vesicles as CRF. The other 50% of the CRF axons contained little or no detectable AVP or AVP precursor-derived peptides. Differential activation of these subpopulations of CRF axons could provide a mechanism by which levels of CRF and AVP in portal plasma could be varied independently.

Animals↗
PubMed1979

Proton magnetic resonance studies on [methionine]-enkephalin and beta-endorphin in aqueous solution.

Proton magnetic resonance studies of [Met5]-enkephalin (lipotropin 61-65) in aqueous solution indicate a conformational preference for the pentapeptide backbone. The structural differences between [Met5]-enkephalin and other, more flexible peptides have been investigated using paramagnetic probe techniques. An outline structure for beta-endorphin (lipotropin 61-91) in aqueous solution is obtained from binding studies using Gd(III) as a relaxation probe.

Animals↗
PubMed1979

Distribution of active and inactive forms of endorphins in rat pituitary and brain.

The recent isolation and identification of alpha-N-acetyl forms of the C-Fragment of lipotropin (beta-endorphin, residues 61-91) and the C'-Fragment (residues 61-87) [Smyth, D.G., Massey, D.E., Zakarian, S. & Finnie, M. (1979) Nature (London) 279, 252-254] has led to a study of their distribution in the pituitary and brain of the rat. Regions were mapped by the method of immunofluorescent staining and the reactive peptides were determined by immunoassay after extraction, gel filtration, and ion exchange chromatography. The major immunoreactive peptides in both lobes of the pituitary were found to be C'-Fragment and N-acetyl C'-Fragment, which are weakly active or inactive as opiates; the C-Fragment and its N-acetyl derivative represented minor components. This indicates that in the rat the circulating "endorphins" released from pituitary would have little morphinomimetic activity. The same four immunoreactive peptides were observed in rat brain. In the hippocampus the C'-Fragment was the principal component in the midbrain there was more C-Fragment but C'-Fragment predominated; in the hypothalamus the C-Fragment was the major peptide, almost to the exclusion of the other peptides. The results demonstrate that the processing of lipotropin is under differential control in anatomically distinct regions of the central nervous system. The processing of lipotropin in the hypothalamus is directed specifically to the production of lipotropin C-Fragment.

Amino Acid Sequence↗
PubMedDate not supplied

Cardiac intervention.

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Angioplasty, Balloon↗