Cyclopropane-derived peptidomimetics. design, synthesis, and evaluation of novel Ras farnesyltransferase inhibitors.

Trisubstituted cyclopropanes have previously been established as rigid replacements of dipeptide arrays in several biological systems. Toward further evaluating the utility of these dipeptide mimics in the design of novel CA(1)A(2)X-based inhibitors of Ras farnesyltransferase (FTase), the conformationally constrained, diastereomeric pseudopeptides CAbuPsi[COcpCO]FM 7-9, the flexible analogue CAbuPsi[CHOHCH(2)]FM (10), and the tetrapeptide CAbuFM (6) were prepared. The orientations of the two peptide backbone substituents and the phenyl group on the cyclopropane rings in 7-9were specifically designed to probe selected topological features of the hydrophobic binding pocket of the A(2) subsite of FTase. The syntheses of the requisite trisubstituted cyclopropane carboxylic acid 22 and the diastereomeric cyclopropyl lactones 32a,b featured diastereoselective intramolecular cyclopropanations of chiral allylic diazoacetates and a new method for introducing side chains onto the C-terminal amino acid of cyclopropane-derived dipeptide replacements via the opening of an N-Boc-aziridine with an organocuprate. These cyclopropane intermediates were then converted into the targeted FTase inhibitors 7-9 by standard peptide coupling techniques. The pseudopeptides 7-9 were found to be competitive inhibitors of Ras FTase with IC(50)s of 1055 nM for 7, 760 nM for 8, and 7200 nM for 9. The flexible analogue 10 of these constrained inhibitors exhibited a IC(50) of 320 nM and hence was slightly more potent than 7 and 8. All of these pseudopeptides were less potent than the tetrapeptide parent CAbuFM (6), which had an IC(50) of 38 nM. Because 7 and 8 are approximately equipotent, it appears that the orientation of the peptide backbone substituents on the cyclopropane rings in 7 and 8 do not have any significant effect on binding affinity and that multiple binding modes are possible without significant changes in affinity. On the other hand, this flexibility does not extend to the orientation of the side chain of the A(2) residue as 7 and 8 were both nearly 1 order of magnitude more potent than 9. Comparison of the relative potencies of 6 and 10 suggests that the amide linkage between the A(1) and the A(2) residues of CA(1)A(2)X-derived FTase inhibitors is important.

Continuous epidural analgesia using fentanyl and bupivacaine after total knee arthroplasty.

Eighty consecutive patients undergoing unilateral total knee arthroplasty received postoperative analgesia consisting of a continuous epidural infusion of fentanyl and bupivacaine. Nineteen patients (24%) were unable to complete the three-day course of epidural infusion: two thirds for technical reasons and one third because of adverse effects. The remaining 61 patients (76%) successfully completed the 72-hour protocol. The benefits in this group included a shorter hospital stay (8.3 versus 9.5 days, p < 0.01) and earlier return of flexion (p < 0.05) as compared with the group that had the epidural catheter removed prematurely. When compared with previous experiences with continuous epidural analgesia using Duramorph and bupivacaine for the first three days after TKA in 56 patients, the current group of 80 patients had shorter average hospitalization (8.6 versus 9.7 days, p < 0.01) and earlier return of flexion (p < 0.001). Patient acceptance was excellent with either agent. Confusion and pruritus were significantly less common with fentanyl, but the incidence of hypotension was increased. Nausea was problematic in both groups. The incidence of respiratory depression was 5% for either opiate. The degree of hypoventilation and treatment required for it were less severe with fentanyl, however.

Evidence for isoleucine as a positive effector of the ilvBN operon in Salmonella typhimurium.

Concerted efforts were directed towards understanding the control of acetohydroxy acid synthase (AHAS) in the gyrB mutant hisU1820 of Salmonella typhimurium. A media shift from valine to valine plus isoleucine causes a dramatic 4 to 5 fold burst of AHAS valine sensitive activity which appears to be dependent on translation. DJ19, an isolated valine sensitive derivative of the gyrB mutant, maintains a dramatic increase in AHAS valine sensitive activity upon the addition of isoleucine to valine supplemented cultures, suggesting that the isoleucine effect is specific for valine sensitive AHAS. Evidence supports isoleucine as a positive effector on valine sensitive AHAS expression and that the gyrB mutation accentuates the isoleucine effect.

Alignment of total knee arthroplasty.

A series of 65 total knee arthroplasties performed by the senior author was evaluated to determine the effect of alignment on outcome. Radiographs and results of clinical examination were reviewed. Sixty-one of the 65 knees were in varus on the mechanical axis (ie, the weight-bearing line passed through the medial compartment). At an average follow-up period of 48 months, alignment was not found to affect incidence or progression of radiolucent lines, changes in tibial metaphyseal density, or clinical outcome (pain or range of motion). The authors were unable to confirm the historical belief that alignment is critical to the durability of cemented total knee arthroplasty, nor that the mechanical axis must pass through the center of the knee joint.

Peripartum changes in the bovine placenta related to fetal membrane retention.

To understand fetal membrane retention in dairy cattle, we examined these tissues in the immediate peripartum period before tissue separation. Placentomes were collected at 270-280 d of gestation from pre-partum Holstein cows (n = 5) and at 1, 3, 6, and 12 h postpartum from a) cows releasing fetal membranes in less than 12 h (n = 7), b) cows retaining fetal membranes for more than 12 h (n = 5), and c) cows induced to calve with dexamethasone (releasing membranes in more than 12 h; n = 5). Subjective evaluations of necrosis, distribution, and condition of binucleate giant and of principal cells were made. Necrotic foci and binucleate giant cells were counted for each interval for which tissue was available. Necrosis, existing prepartum, was identical to that observed at 1 h postpartum in all treatment groups (P > 0.05). Necrosis gradually increased in all treatment groups with time (P < 0.05); thus necrosis is unrelated to initiation of calving and is indirectly related to fetal membrane retention. Many binucleate giant cells were observed prepartum. In cows releasing fetal membranes normally, a significant (P < 0.05) decline in these cell numbers had occurred by 1 h postpartum. When fetal membrane retention occurred, no such decrease in binucleate giant cells was observed before 12 h postpartum. Loss of binucleate giant cells appears necessary for, or must occur with, separation of fetal membranes.

Epizootiology, pathology, and microbiology of an outbreak of urolithiasis in chickens.

An outbreak of urolithiasis that doubled the annual mortality rate of chickens in a large flock of table-egg-layers is described. Despite the presence of a large unilateral urolith and/or severe renal atrophy, the layers often maintained active egg production and apparent homeostasis until a small urolith blocked the ureteral flow from the contralateral kidney. This terminal episode appeared to produce acute obstructive renal failure, rapidly developing visceral gout (visceral urate deposition), uremia, and death. The atrophy observed appeared to be acquired and progressive. Histologic features in the kidneys were acute to chronic glomerulonephritis, interstitial nephritis, and pyelonephritis. Epizootiologic and microbiologic studies indicated that a combination of infectious and noninfectious mechanisms may have been involved. Causative roles for calcium-phosphate imbalance, infectious bronchitis (IB), Newcastle disease (ND), and adenovirus or reovirus infections could be neither excluded nor confirmed. Contributory factors may have been spray ND-IB and other vaccinations of 15-week-old ND-IB-susceptible pullets, water deprivation, shipping stress, Mycoplasma synoviae infection, immune complex disease, and mycotoxins.

Communicating company objectives.

Knowing and understanding company objectives will not help employees solve every work-related problem, but, in the long run, such knowledge will contribute to more efficient and productive operations.