Ligation of nicked SV40 dna in a polyethylene glycol-condensed state as a test for net coiling.
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DNA Ligases↗
Biomedical subjects
J D Griffith
Publications and source records attributed to J D Griffith.
The multifunctional role of histone H1, probed with the SV40 minichromosome.
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Binding Sites↗
Electron microscope visualization of chromatin and other DNA-protein complexes.
In this review we have tried to cover the direct mounting techniques currently in use and, through micrographs kindly supplied by our colleagues, to illustrate uses of the different methods. For the novice, it is important to select one technique, taking time to become acquainted with its use in visualizing simple test samples before applying it to examine more complex structures. We have tried to emphasize the importance of controlling the fixation for two reasons. First, confidence in the fixation step allows one to correlate structures observed by EM with structures present in solution. Second, fixation of otherwise labile samples allows one to apply powerful purification techniques.
Chromatin↗
Lithium: effects on subjective functioning and morphine-induced euphoria.
The therapeutic usefulness of lithium in decreasing the euphoria and other symptoms associated with manic behavior and the hypothesis of a common final mechanism for elevations in mood have led to speculation that lithium may block the euphoria induced by drugs of abuse. In this study, lithium alone was antieuphoric in drug-free opiate addicts and, further, did not block morphine-induced euphoria.
Clinical Trials as Topic↗
Therapeutic usefulness of propoxyphene napsylate in narcotic addiction.
The maximum doses of propoxyphene napsylate used to treat heroin addicts produce a degree of morphine-like activity equal to that produced by 20 to 25 mg/day of subcutaneously given morphine or 10 mg/day orally given methadone. This degree of activity wound be sufficient to ameliorate abstinence even in patients dependent on large doses of narcotics--an observation that supports the utility of propoxyphene napsylate in detoxification. On the other hand, only patients taking 10 mg/day or less of parenterally administered heroin could be maintained on maximum subtoxic levels of propoxyphene napsylate without abstinence signs or symptoms suggesting that propoxyphene napsylate would be less useful in maintenance therapy.
Administration, Oral↗
Azidomorphine: subjective effects and suppression of morphine abstinence.
In man, azidomorphine, a new morphine congener, constricted pupils, produced morphine-like subjective effects and euphoria, and suppressed the morphine abstinence syndrome. Azidomorphine was 10 to 50 times as potent as morphine. It is concluded that in man azidomorphine is a typical morphine-like drug.
Azides↗
Visualization of prokaryotic DNA in a regularly condensed chromatin-like fiber.
Electron microscopy of disrupted Escherichia coli cells under certain conditions revealed loops of a fiber 120 A in diameter which were attached to the cell envelope and showed a 130 A repeating beaded substructure. These fibers were detected only when the cells were lysed in 0.15 M NaCl solutions directly on the electron microscope supporting films and if the dehydration steps began within 2 min of lysis. Under these conditions examination of cells lysogenic for phage lambda after superinfection with lambda wild type or deletion mutants disclosed short loops of a 120 A diameter fiber free of the cell envelope. Because the contour length of these loops was proportionate to the DNA content of the superinfecting lambda phage, it was concluded that the fibers contained DNA condensed 6.5-fold in blocks of about 250 base pairs.
Chromatin↗
Etorphine in man. I. Subjective effects and suppression of morphine abstinence.
The effects of etorphine, a potent morphine-like drug, were qualitatively and quantitatively compared to those of morphine. In nondependent subjects, etorphine in doses of 0.025, 0.050, and 0.100 mg produced pupillary constriction and morphine-like subjective effects and euphoria. Etorphine was 500 times as potent as morphine, with a very rapid onset and short duration of action. In morphine-dependent subjects, etorphine suppressed abstinence but for a shorter period than morphine. These studies indicate that in man etorphine is a morphine-like drug with a high abuse potential.
Clinical Trials as Topic↗
A comparison of fenfluramine and amphetamine in man.
dl-Fenfluramine hydrochloride (60, 120, 240 mg), d-amphetamine sulfate (20, 40 mg), and placebo were compared in 8 postaddict volunteers, each dose given orally in random sequence at weekly intervals using a double-blind crossover design. Fenfluramine had little effect on blood pressure and temperature, but caused a marked dilation of pupils, whereas amphetamine was a potent vasopressor and a weak mydriatic. While fenfluramine produced euphoria in some subjects, its overall effects were unpleasant, sedative, and qualitatively different from amphetamine. Three subjects given 240 mg of fenfluramine experienced brief but vivid hallucinogenic episodes characterized by olfactory, visual, and somatic hallucinations, abrupt polar changes in mood, time distortion, fleeting paranoia, and sexual ideation. These observations indicate that fenfluramine is a hallucinogenic agent with a pharmacologic profile in man that is not amphetamine-like.
Adult↗