Biomedical subjects
Publications and source records attributed to E Lear.
In this paper, we describe an automated system for distributing updates to the GenBank nucleic acid sequence database, using the Usenet news system as the underlying transport mechanism. Our system allows new loci to be distributed as soon as the sequences are available, over existing networks, using existing Usenet software and infrastructure currently available on a wide range of computer systems.
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Twelve cats were assigned equally to two groups, one with normal, and the other with artificially-increased intracranial pressure. When suxamethonium was administered to these animals, the intracranial pressure increased in both groups, irrespective of their baseline intracranial pressure. When the same dose of suxamethonium was administered after pretreatment with thiopentone in both groups of animals, the intracranial pressure again increased from the control values.
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The effects of commercial and crystalline solutions of chloroprocaine (CP) (1.6 X 10(-3)-0.4 X 10(-3)M) and sodium bisulfite (SB) (0.8 X 10(-3)-0.08 X 10(-3)M) were studied on the multiplication of human neuroblastoma cells. These cells were chosen because of putative neurotoxicity associated with CP; cell multiplication (measured as colony-forming ability-CFA) was studied because CFA is a reliable in vitro test for drug toxicity at the cellular level. CFA was dramatically reduced (86%) after 20-hr exposure to commercial solutions of CP. Shorter exposure times (3 hr) resulted in a marginal toxic effect (32%). At similar concentrations and after 20-hr exposure time, CP crystalline solutions induced a 37.5% inhibition that decreased with decreased time in culture. Sodium bisulfite reduced cell multiplication to a degree that varied with different samples of SB. With a 3-hr exposure time, CFA was reduced 72-92% by SB-1 and 57-72% by SB-2. The variability of SB toxicity and the difference in toxicity with commercial and crystalline solutions of CP are discussed in terms of possible clinical toxicity.
The commonly used vasodilators sodium nitroprusside and nitroglycerin increase intracranial pressure (ICP) and cause tachycardia. Since diltiazem is also a vasodilator, we designed this experiment in cats to study its effect on intracranial pressure and heart rate (HR). Twelve cats were assigned to two equal groups. One group had normal ICP (N-ICP), while in the other the ICP was raised artificially (AR-ICP) by placing a balloon into the intracranial extradural space. Both groups received an infusion of diltiazem to decrease the mean blood pressure (BP), which was maintained 30 per cent below the baseline value for 15 minutes. Diltiazem caused no significant change in ICP (5.7 +/- 1 to 6.7 +/- 1.5 mmHg, p less than 0.01) in cats with N-ICP while in cats with AR-ICP, the increase from 26.9 +/- 0.5 to 34.0 +/- 1.9 mmHg was significant (p less than 0.006). HR decreased significantly during the diltiazem infusion in both groups.
Chloroprocaine, an aminoester local anesthetic commonly used for epidural block, has been found to induce interspecies somatic cell hybrids in vitro. Mixed cultures of human amniocytes and mouse hepatoma cells, deficient in hypoxanthine phosphoribosyl transferase, were exposed to 1.6, 0.8, or 0.4 X 10(-3)M chloroprocaine for 3 hr at 37 degrees C, then maintained for 3 weeks in a double-selective medium of hypoxanthine, aminopterin, and thymidine (HAT) and ouabain to eliminate the unfused parental cells. Clones of actively multiplying cells appeared in cultures exposed to 1.6 and 0.8 X 10(-3)M chloroprocaine. Chromosome analysis confirmed they were hybrids. Cultures treated with 0.8 X 10(-3)M chloroprocaine exhibited the highest frequency of cell hybridization (8.8 X 10(-5). The hybrid clones bore the morphologic characteristics of both parents although their growth pattern closely resembled the mouse parent. Procaine, sodium bisulfite (the antioxidant present in the commercial solutions of chloroprocaine), and the two chloroprocaine metabolites, chloroaminobenzoic acid and diethylaminoethanol, were nonfusogenic. The hybridogenic effect of chloroprocaine has not been previously described with other local anesthetics.
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We describe a rapid procedure for quantitating theophylline in 100-mul plasma samples by use of a gas-liquid chromatograph equipped with a flame ionization detector. This methos is especially useful for monitoring theophylline concentrations in serum or plasma of infants, because sufficiently large blood samples can be readily obtained from a heel prick. The method is specific for theophylline in the presence of caffeine, theobromine and phenobarbital. For plasma concentrations equal to or greater than 5 mg/liter the average daily coefficient of variation was less than 7% while the coefficient of variation from day to day was less than 11%. The same approach can also be used to measure concentrations of phenobarbital in small volumes of plasma or serum, and is readily adapted to determination of theophylline and phenobarbital in larger samples.
The safe conduct of anesthesia demands careful evaluation of the previous experience of patients under anesthesia and surgical operation, as well as that of their families. Untoward responses that may recur with subsequent anesthetic procedures should be documented and patients informed, as the need dictates. Two cases of prolonged apnea following single intubating doses of succinylcholine could not have been predicted by the patient's preanesthetic history. As a result of these problems, the authors recommend more careful preanesthetic history-taking with reference to patients' prior anesthetic experiences.