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Biomedical subjects

D Newton

Publications and source records attributed to D Newton.

At least 55 records · Page 3Linked to original sources
PubMed1984

Elevation of mercury in human blood from controlled chronic ingestion of methylmercury in fish.

The relationship between the intake of methylmercury in fish and mercury in blood has been investigated in man. The intakes of methylmercury were carefully controlled and lay in the range 40-230 micrograms/day, the Provisional Tolerable Weekly Intake is equivalent to about 30 micrograms/day. The results indicate that a daily intake of 1 microgram methylmercury would, at equilibrium, produce a blood mercury concentration of 0.8 micrograms/kg. There is a good close-to-linear correlation between methylmercury intake and blood mercury concentrations within the wide range of intakes employed.

Adult↗
PubMed1983

Differential clearance of plutonium and americium oxides from the human lung.

External X- and gamma-ray counting techniques have been used to study the retention of 238PuO2 and 241AmO2 in the lungs of a worker between 7 and 869 days after simultaneous exposure to aerosols of both oxides. From these data and measurements of early faecal excretion, it is concluded that approx. 50% of the amount of each nuclide initially deposited in the subject was removed during the first few days by ciliary clearance mechanisms. The lung clearance patterns of the other 50% differed for the two nuclides. The 238Pu was apparently cleared with a biological half-life of approximately 800 days, predominantly by systemic or lymphatic uptake, with at least part of the translocated material being subsequently deposited in bone. There was no evidence for the presence of a 30-day component of lung clearance, such as has been suggested elsewhere. In contrast, most of the residual 241Am was cleared relatively quickly, with a half-life of approximately 11 days, although a small proportion was apparently subject to long-term retention, with a half-life of approximately 900 days. The data for both oxides conflict in important respects with the patterns of lung clearance postulated by the ICRP.

Aerosols↗
PubMed1982

Epidemiology of adverse reactions in anaesthesia in Germany and the Netherlands.

We consider 292 anaphylactoid reactions from the own material (1964-1980) out of two different Departments of anesthesiology to attempt to review the continental epidemiology of this life-threatening adverse drug reaction. We conclude the following: The specialty of this type of adverse reaction is likely to prove a special separating name i.e. "anaphylactoid reaction". The overall frequency can be estimated for 1 : 400-600 in anesthesiology, a preponderance of females may be possible. There is no predictability of the reaction, not even by sophisticated history. But it is possible to avoid the development of severe shock by early diagnosis and immediate full causative therapy. With growing experience in diagnosis and therapy the mortality of anaphylactoid reaction should be irrelevant in the near future.

Adjuvants, Anesthesia↗
PubMed1982

Mithramycin- and triethylene melamine- induced sperm abnormalities in Lakeview hamsters.

The sperm abnormality-inducing action of two potential mutagenic agents mithramycin and triethylene melamine (TEM), in inbred Lakeview hamsters was studied and results compared with similar investigations in mouse. Test hamsters received subacute intraperitoneal exposures ranging from 0.01 to 0.25 mg/kg body weight with either agent for 5 consecutive days. Testis weights, epididymal sperm numbers, and body weights were also monitored at weeks 1, 4, and 10 after treatment. Mithramycin-treated hamsters showed 21 times more sperm abnormalities than control (25% vs. 1.2%) whereas TEM elevated sperm abnormalities by eight fold. The frequency and type of aberrant sperm varied with dose and time, being the highest at weeks 1 or 4, rather than week 10, with either agent. Sperm number and testis weights remained depressed considerably from 4 to 10 weeks after treatment with either agent. Body weights in chemically treated hamsters remained within 28% of control for the test period. Even though our findings were in general agreement with those reported for mouse, the magnitude of the response and the stage of spermatogenic sensitivity in the chemical induction of sperm abnormalities in the two species were different.

Animals↗
PubMed1981

Pharmacodynamics and reversal of benzodiazepine-ketamine ataranalgesia.

We describe the combined use of ketamine with benzodiazepines, which produces a state of ataranalgesia. From our investigation of the combination of ketamine with three such drugs--diazepam, flunitrazepam and midazolam--we conclude that the ketamine-midazolam sequence is the best combination in terms of preservation of physiological homeostasis and recovery time. In addition, we describe the reversal of ketamine-diazepam ataranalgesia by the new cholinergic agonist, 4-aminopyridine.

Aminopyridines↗
PubMed1980

Fat digestion in patients with bile acid malabsorption but minimal steatorrhea.

Patients with an interrupted enterohepatic circulation of bile acids and minimal or no steatorrhea were studied to determine if their fat absorption was aided by compensatory mechanisms which delivered increased amounts of lipid to the aqueous phase of post-prandial duodenal fluid. The data suggested that the molar stoichiometry of association of fatty acid and bile acid in an aggregated (micelle) form was reduced in the patients (0.8) as compared to normals (1.4). Each patient had either normal sized or undetectable micelles; one patient had a large fatty acid-rich aggregated species. The bile acid composition of the whole duodenal fluid was found to have an increased proportion of dihydroxy bile acids which were conjugated with glycine. There was a selective precipitation of dihydroxybile acids from the aqueous phase, such that the patients had a normal proportion of these bile acids in the aqueous phase. We were unable to identify a consistent compensatory mechanism whereby these patients could increase the concentration of lipid in the aqueous phase which would have led to a better understanding of their minimal steatorrhea. We believe that the reduced stoichiometry of aggregated fatty acid to aggregated bile acid is in part due to the altered bile acid pool composition of these patients.

Bile Acids and Salts↗
PubMed1980

The neuromuscular blocking action of ORG NC 45, a new pancuronium derivative, in anaesthetized patients. A pilot study.

The neuromuscular blocking effects of the new monoquaternary analogue of pancuronium, Org NC 45, have been investigated in anaesthetized patients. In different doses administered as a single i.v. bolus or as an initial bolus followed by several small maintenance doses or by a continuous infusion. Org NC 45 appears to be approximately as potent as pancuronium, but has a more rapid onset of action, considerably shorter duration of action and faster recovery rate than pancuronium. It showed no cumulative effects even after 10 maintenance doses were injected in succession. Doses of 0.08 mg kg-1 provided ideal intubating conditions in 90--95 s. Infusions of Org NC 45 provided much smoother control of neuromuscular blockade than did pancuronium. No cardiovascular side-effects were noted even at the greatest dose (0.12 mg kg-1) used. Org NC 45 has clear advantages over pancuronium and represents a potentially valuable addition to the armamentarium of clinically useful muscle relaxants.

Anesthesia, General↗