REPAIR OF THE QUADRICEPS APPARATUS FOLLOWING PATELLECTOMY IN RECENT FRACTURES OF THE PATELLA: A NEW TECHNIQUE,WITH RESULTS1

The importance of “double tourniquet” technique in repair of the quadriceps mechanism after total patellectomy in recent fractures of the patella is described and its advantages are discussed. The results following this method of repair in 17 total patellectomies have been studied and discussed.     

Ascorbic acid and melanogenesis

The ascorbic acid contents of skin, plasma and urine were estimated in 12 vitiligo cases, one albino and 10 normal subjects. All the estimations were repeated after saturation with ascorbic acid. There was no difference between the two groups with regard to the ascorbic acid contents of their plasma or urine. The ascorbic acid level of vitiliginous skin was decreased; however, this difference just falls short of significance at the level P = 0.05. Further investigations with a larger group of patients are indicated.     

Synthesis and antibacterial action of cecropin and proline-arginine-rich peptides from pig intestine

Dedicated to Professor Koji Nakanishi on the occasion of his 70th birthday. Two antimicrobial peptides, cecropin P1 (CPl), with a C-terminal carboxyl group, and PR-39, with an amidated C-terminus, are found in the small intestine of the pig. Each is active against both Gram-positive and Gram-negative bacteria. We have synthesized these peptides and several analogs, including the d -enantiomers and the retro sequences, each with a free or acetylated amino terminus. The CPI amide was also prepared. The retro CP1 peptides were much less active than the parent CPl peptide, confirming the importance of sequence or the amide bond and helix dipole direction, and the N^α-acetyl peptides were also less active, indicating that a free amino terminus is essential for high activity. The ratio of the lethal concentration of L/D isomers of CP1 is less than 1 for Gram-negative, but greater than 1 for Gram-positive bacteria. PR-39 showed no significant chiral selectivity toward Escherichia coli, Bacillus subtilis and Streptococcus pyogenes, but the l /d ratio was high for Pseudomonas aeruginosa (66), and very high for Staphylococcus aureus (>1000). In the latter case the lethal concentration for the d -isomer was 0.57 μ whereas this organism was quite resistant to the l -isomer (>600μ). Thus the enantiomers of CP1 and PR-39 are not equally active for all species. In a plate assay with a very small log-phase inoculum of Staph. aureus, D-PR-39 produced a clear zone of killing surrounded by a zone of stimulated growth. After prolonged incubation the two zones became one clear zone. Addition of D-PR-39 to the wells of a dense turbid plate of growing cells showed a cleared zone for each of the test organisms, indicating that PR-39 lyses the bacteria rather than simply inhibiting their multiplication. © Munksgaard 1997.     

Synthesis and study of normal,enantio, retro,and retroenantio isomers of cecropin A-melittin hybrids,their end group effects and selective enzyme inactivation

In our effort to understand the structural requirements for the antimicrobial activity of cecropin A (CA) and melittin (M), we synthesized the normal, enantio, retro and retroenantio hybrid analogs; we related activity to their sequence, chirality, amide bond direction (helix dipole) and end group charges. To compare the effect of the end groups, each of these analogs was synthesized both with an acid and an amide C-terminus and also with and without an N^α-acetyl N-terminus. The all-l - and all-d -enantiomers of several cecropin-melittin hybrids were previously found to be equally potent against several bacterial species, and no chiral effect was observed. This general rule has now been confirmed and extended. However, two exceptions have been found. All-l -CA(1-13)M(1-13) acid was 5 times and 9 times less potent than the all-d -analog, respectively, toward Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. A11-l -CA(1-7)M(2-9) acid was 5 times and 14 times less active against S. aureus and P. aeruginosa, respectively, than its all-d acid isomer. The corresponding d - and l -retro analogs differed only marginally. A role for proteolytic enzymes has been implicated as a cause for these differences in the activities of l - and d -enantiomers. In all cases, blocking the α-amine by acetylation had no significant effect on potency. The retro and retroenantio analogs of CA(1-13)M(1-13) acid were as potent as their normal and enantio analogs against all the test bacteria. The C-terminal amides also showed similar potency against four test bacteria. It should be noted that the negative end of the helix dipole of a normal peptide points toward the C-terminus, whereas it points away in the case of a retro derivative when viewed in the direction of the normal sequence.