Search

In this review we have critically evaluated the application of the diagenetic racemization of amino acids to geochronology and geothermometry. Although there has been enthusiastic support given to this new method, it is our opinion that recent developments suggest a more cautious approach. We have discussed the pitfalls and inhereent complications, while outlining the advances which have been accomplished. We conclude that this is an innovative approach which will add valuable information to the scientific literature. However, since our fundamental understanding of diagnetic racemization is still limited, many of the age and paleotemperature estimates which have been assigned to fossil specimens may be unreliable.

In a double blind study, seven volunteers were given lidocaine 0.75 per cent and bupivacaine 0.25 per cent in two trials to compare the agents for use in intravenous regional analgesia. There was no significant difference between the two agents in the duration of analgesia after removal of the tourniquet. Bupivacaine produced fewer side effects. It also consistently produced persistent analgesia on the posterolateral aspect of the forearm.

Acetaldehyde is a toxic substance common to heavy drinking of alcohol and heavy smoking of cigarettes. It has been implicated thereby in diseases of the cardiovascular, respiratory, and central nervous systems. Protection against acetaldehyde toxicity (i.e. anesthesia and lethality) was studied in rats by oral intubation of test compounds 30-45 minutes prior to oral intubation of a standardized oral LD 90 dose (18 millimoles/kilogram) of acetaldehyde. Animals were monitored for anesthesia (loss of righting reflexes) and lethality for 72 hours. A total of 18 compounds was tested. L-ascorbic acid at 2 millimoles/kilogram (mM/kg) showed moderate protection against anesthesia and marked protection against lethality. Greatest protection against anesthesia and lethality was obtained at 2 m M/kg with each of the following: L-cysteine, N-acetyl-L-cysteine, thiamin-HCl, sodium metabisulfite, and L-cysteic acid. A combination of L-ascorbic acid with L-cysteine, and thiamin-HCl at reduced dose levels (2.0, 1.0 and 0.3 mM/kg, respectively) gave virtually complete protection. A detailed literature review is presented of the rationale and significance of these findings. Our findings could point the way to a possible build-up of natural protection against the chronic body insult of acetaldehyde arising from heavy drinking of alcohol and heavy smoking of cigarettes.

A natural membrane was employed in an automated diffusion system. A mature male Mongolian gerbil sebaceous gland pad was excised and mounted into a suitable retainer so that the external surface was oriented toward the concentrated aqueous drug solution. Aqueous solutions of benzoic acid and the three commonly used parabens were studied. The gerbil sebaceous pad effectively prevented any diffusion of these drug solutions within 15 hr. Water by itself, however, was transported through the skin even against a pressure gradient. Although no apparent diffusion of these compounds occurred, a significant amount of drug was retained by the sebaceous pad. An expression for membrane-water partition coefficients could be calculated. Based upon thicknesses of natural and synthetic membranes, theoretical approximations of diffusion rates were found using lag time calculations.

The usefulness of a new oral contraceptive compound containing norethindrone 5 mg. and mestranol 0.075 mg. (Ortho-Novum) was studied. One hundred and seventeen private patients used this preparation for a total of 998 menstrual cycles. There were no pregnancies. Side effects were minimal and caused few (11 patients) to discontinue use. The most significant of these was weight gain and a premenstrual tension syndrome including nausea, breakthrough bleeding and skin effects. Other symptoms were minor and easily controlled. Instruction in use of the preparation is easy. Patient acceptance is excellent. Possible masculinizing effects, liver damage, or harmful effects on the uterus were checked specifically by laboratory evaluation; no significant abnormal findings were noted.This appears to be an effective oral contraceptive which is well accepted by the patient and which produced no serious side effects as used in this study.