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F L Murphy

Publications and source records attributed to F L Murphy.

6 recordsLinked to original sources
PubMed1992

RNA substrate binding site in the catalytic core of the Tetrahymena ribozyme.

In catalysis by group I introns, the helix (P1) containing the RNA cleavage site must be positioned next to the guanosine binding site. We have identified a conserved adenine in the catalytic core that contributes to the stability of this arrangement and propose that it accepts a hydrogen bond from a specific 2'-OH in P1. Such base-backbone tertiary interactions may be generally important to the organization of RNA tertiary structure.

Adenine↗
PubMed1992

Alkalinization of mepivacaine for axillary block.

We examined the onset and distribution of sensory blockade, the onset of motor blockade, and venous mepivacaine concentrations after axillary block with 1.25% mepivacaine with and without bicarbonate. There were no statistically significant differences between the alkalinized and placebo groups with respect to distribution of analgesia or anesthesia, time to onset of analgesia, or time to onset of paresis. However, alkalinization significantly decreased the time to onset of anesthesia in the medial cutaneous nerve of the forearm, the median nerve, and the ulnar nerve, as well as the time to onset of paralysis. Concentrations of mepivacaine in venous blood did not differ significantly. We conclude that alkalinized mepivacaine offers the advantage of quicker onset of more profound blockade in several terminal nerve distributions.

Adult↗
PubMed1990

Low-dose lovastatin safely lowers cholesterol after cardiac transplantation.

Hypercholesterolemia occurs in many cardiac transplant patients and may aggravate graft coronary arteriopathy as well as contributing to peripheral vascular disease. Lovastatin, which inhibits 3-hydroxy-3-methylglutaryl coenzyme A reductase, in doses of 40-80 mg/day effectively lowers cholesterol in the general cardiac population but has been associated with rhabdomyolysis in cardiac transplant recipients. To determine whether lower doses of lovastatin would be effective and safe for lowering cholesterol after cardiac transplantation, 44 patients with blood cholesterol greater than 200 mg/dl at least 6 months after cardiac transplantation received 10-20 mg lovastatin daily. In addition, lovastatin enzyme inhibitor level was assayed in six patients to determine whether metabolism of the drug was abnormal. Lovastatin decreased total cholesterol by 28% from 282 +/- 54 to 208 +/- 62 mg/dl (p less than 0.005), primarily because of reduction in the low-density lipoprotein fractions, and was well-tolerated without any symptoms or abnormal creatine phosphokinase levels in 43 of 44 patients. One patient developed rhabdomyolysis and reversible renal failure when lovastatin was increased to 40 mg daily. Enzyme inhibitor levels in the six transplant patients were 4.2-7.8 times higher than those measured in normal volunteers. Low-dose lovastatin effectively lowers cholesterol in patients after transplantation, but metabolism is altered, perhaps by cyclosporine. Monitoring of enzyme inhibitor levels may be required to allow safe administration of this drug to cardiac transplant recipients.

Cholesterol↗
PubMed1989

Alteration of substrate specificity for the endoribonucleolytic cleavage of RNA by the Tetrahymena ribozyme.

A shortened form of the intervening sequence of the self-splicing RNA from Tetrahymena thermophila catalyzes sequence-specific cleavage of RNA. Cleavage site selection involves a base-pairing interaction between the substrate RNA and a binding site within the intervening sequence. Single-base changes in this binding site were previously shown to alter substrate specificity in a predictable manner. To examine the generality with which substrate specificity can be altered, six variant catalytic RNAs (ribozymes) have been produced with two- or three-base changes in the active site. Each ribozyme cleaves its predicted substrate. The conditions required for good reactivity and for discrimination against cleavage at mismatched sites vary and were independently determined for each ribozyme.

Animals↗