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Levin Y, Khare RK, Abel G, Hill D, Eriotou-Bargiota E, Becker JM, Naider F. Histidine2 of the alpha-factor of Saccharomyces cerevisiae is not essential for binding to its receptor or for biological activity. Biochemistry 1993; 32:8199-206. [PMID: 8394129 DOI: 10.1021/bi00083a021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Seven His2 analogs of the Saccharomyces cerevisiae [Nle12]alpha-factor, WXWLQLKPGQP(Nle)Y, where X = beta-D-thienylalanine, beta-L-thienylalanine, 1-D-methylhistidine, 1-L-methylhistidine, 3-D-methylhistidine, 3-L-methylhistidine, and beta-3-L-pyridylalanine, were synthesized and purified to homogeneity. Assays were carried out on binding to the alpha-factor receptor and of biological activity determined by either growth arrest or morphological changes in target cells. In the L-isomer, replacement of the imidazole of histidine by thiophene or 3-pyridyl groups or derivatization of either nitrogen of the imidazole ring by methylation resulted in a 2-100-fold decrease in bioactivity. D-Isomers of the beta-thienylalanyl-, 1-methylhistidinyl-, or 3-methylhistidinyl-alpha-factors did not possess measurable bioactivity with the exception of comparatively low activity of the 3-D-methylhistidinyl and 1-D-methylhistidinyl-alpha-factors in the morphogenesis assay. In contrast, both active and inactive analogs demonstrated binding affinities 10-20-fold less than that of [Nle12]alpha-factor. These results indicate that the histidine residue of alpha-factor is not required for binding to the receptor or for biological activity and that bioactivity and binding can be dissociated through the use of pheromone analogs.
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Brooks DC, Becker JM, Connors PJ, Carr-Locke DL. Management of bile leaks following laparoscopic cholecystectomy. Surg Endosc 1993; 7:292-5. [PMID: 8351598 DOI: 10.1007/bf00725942] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In a series of 650 consecutive laparoscopic cholecystectomies, nine bile leaks were identified (1.4%). Patients with bile leaks presented clinically at a mean of 4.9 days (range: 3-8 days) after surgery complaining of diffuse abdominal pain, ileus, and nausea. Laboratory values for complete blood counts and liver function tests were all mildly elevated. Definitive diagnosis was made on the basis of abnormal hepatobiliary scintigraphy. Management strategies included laparotomy and drain placement (n = 1), laparoscopy and drain placement (n = 3), ERCP and drainage (n = 4), and CT-guided percutaneous drainage (n = 1). When the etiology of the leakage was identified, it was most commonly either dysfunction of the cystic duct clips (n = 3) or leakage from a disrupted duct of Luschka (n = 2). The source of the remaining leaks (n = 4) was never determined. We conclude that bile leaks are an uncommon cause of morbidity following laparoscopic cholecystectomy. Diagnosis can usually be made with nuclear medicine biliary tract scans and a variety of managements alternatives are successful in treating this complication.
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153
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Becker JM. Ileal pouch-anal anastomosis: current status and controversies. Surgery 1993; 113:599-602. [PMID: 8506515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Clair DG, Carr-Locke DL, Becker JM, Brooks DC. Routine cholangiography is not warranted during laparoscopic cholecystectomy. ARCHIVES OF SURGERY (CHICAGO, ILL. : 1960) 1993; 128:551-4; discussion 554-5. [PMID: 8489389 DOI: 10.1001/archsurg.1993.01420170085012] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The role of intraoperative cholangiography during laparoscopic cholecystectomy was prospectively evaluated in 514 patients undergoing laparoscopic cholecystectomy. Before surgery, all patients were assigned to one of three groups depending on the likelihood of their having common bile duct stones. Stratification was based on objective historical, laboratory, or radiologic criteria. In 453 patients deemed unlikely to have stones, laparoscopic cholecystectomy was performed without cholangiography. Of these patients, four had retained stones (0.9%). In 25 patients likely to have stones, preoperative endoscopic retrograde cholangiopancreatography identified stones in six patients (24%). In 36 patients whose likelihood of having stones was deemed indeterminate, intraoperative cholangiography was performed at laparoscopic cholecystectomy. A common bile duct stone was identified in one patient (2.8%). One common bile duct injury occurred in the group deemed unlikely to have stones, and this injury would not have been prevented by intraoperative cholangiography. We conclude that preoperative assessment will identify common bile duct stones and that routine cholangiography is not warranted. Meticulous dissection of the cystic duct at its origin at the infundibulum will prevent common bile duct injury.
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Gounarides JS, Broido MS, Becker JM, Naider FR. Conformational analysis of [D-Ala9]alpha-factor and [L-Ala9]alpha-factor in solution and in the presence of lipid. Biochemistry 1993; 32:908-17. [PMID: 8422395 DOI: 10.1021/bi00054a023] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The conformations in solution and in the presence of lipid vesicles of [D-Ala9] and [L-Ala9] analogues of the alpha-factor (WHWLQLKPGQPMY) from the yeast Saccharomyces cerevisiae were examined by NMR spectroscopy. Although both peptides are flexible molecules, NOE and NH d delta/dT data indicate that the [D-Ala9]alpha-factor analogue in DMSO and aqueous solution adopts a type II beta-turn about residues 8 and 9. In contrast, various NMR parameters for the less active [L-Ala9] analogue do not provide evidence for a regular secondary structure in solution. Transfer NOE data indicate that for both peptides binding to the lipid is strongest for the N-terminal residues. The C-terminus of the [D-Ala9] analogue appears to be more constrained in the bound state than the C-terminus of the [L-Ala9] analogue. This result is consistent with transfer NOE evidence that the type II beta-turn conformation of the [D-Ala9]alpha-factor is maintained in the lipid bound state.
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156
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Brooks DC, Becker JM. A simplified technique for open laparoscopy using disposable trocars. JOURNAL OF LAPAROENDOSCOPIC SURGERY 1992; 2:357-9. [PMID: 1490003 DOI: 10.1089/lps.1992.2.357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An easily accomplished method for performing open laparoscopy with disposable trocars is presented. This technique provides for safe entry into the peritoneum and subsequently facilitates removal of the gallbladder and any larger stones at the completion of the procedure.
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Basrai MA, Zhang HL, Miller D, Naider F, Becker JM. Toxicity of oxalysine and oxalysine-containing peptides against Candida albicans: regulation of peptide transport by amino acids. JOURNAL OF GENERAL MICROBIOLOGY 1992; 138:2353-62. [PMID: 1479355 DOI: 10.1099/00221287-138-11-2353] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A lysine antimetabolite, L-4-oxalysine [H2NCH2CH2OCH2CH(NH2)COOH], and oxalysine-containing di-, tri-, tetra- and pentapeptides inhibited growth of Candida albicans H317. Micromolar amounts of amino acids were found to overcome ammonium repression of the di- and tripeptide transport system(s) in strain H317. Several amino acids increased the toxicity of oxalysine-containing di- and tripeptides for C. albicans with little or no increase in toxicity of oxalysine or oxalysine-containing tetra- and pentapeptides. L-Lysine completely reversed the toxicity of oxalysine by competing with the transport of oxalysine into the cells. In contrast, L-lysine increased the toxicity of oxalysine-containing di- and tripeptides, but had no effect on the toxicity of oxalysine-containing tetra- and pentapeptides. Incubation of cells with L-lysine for 4 h resulted in a 15-fold increase in the rate of transport of radiolabelled dileucine, indicating that increased sensitivity of C. albicans to some toxic peptides in the presence of L-lysine may be attributed to an increased rate of transport of these peptides. Our results indicate that the dipeptide and tripeptide transport system(s) of C. albicans are regulated by micromolar amounts of amino acids in a similar fashion to the regulation of peptide transport in Saccharomyces cerevisiae and that multiple peptide transport systems differentially regulated by various nitrogen sources and amino acids exist in C. albicans.
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Zenilman ME, Parodi JE, Becker JM. Preservation and propagation of cyclic myoelectric activity after feeding in rat small intestine. THE AMERICAN JOURNAL OF PHYSIOLOGY 1992; 263:G248-53. [PMID: 1514636 DOI: 10.1152/ajpgi.1992.263.2.g248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The cyclic nature and distal propagation of the fasting migrating motor complex (MMC) of the small intestine have been well described. The fate of the MMC after feeding, however, has not been elucidated. We used time series analysis with fast Fourier transforms (FFT) to study myoelectric cycling before and after feeding. Ten rats were chronically prepared with bipolar electrodes secured to the duodenum and proximal jejunum. Spikeburst frequency was recorded before and after feeding simple nutrients. During fasting, cyclic activity occurred at the MMC frequency. Although after feeding this periodicity appeared disrupted, FFT analysis showed persistent cycling at the fasted (MMC) rate. Digital filtering of data at the MMC frequency isolated cycling from background noise during both fasted and fed states and showed a depression in the amplitude of the waveform after feeding. Root-mean-square analysis of the waveform confirmed statistically significant depression of amplitude by 47-57%. The waveform propagated from the duodenum to the jejunum during both the fasted and fed state at an unchanged rate. We conclude that factors controlling myoelectric cycling during the fasted state persist after feeding, allowing continued net abroad propulsion of food.
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Becker JM, Shanley PJ. Defending the healthcare fraud case: parallel proceedings and collateral consequences. DELAWARE MEDICAL JOURNAL 1992; 64:393-8. [PMID: 1451851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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160
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Naider F, Gounarides J, Xue CB, Bargiota E, Becker JM. Studies on the yeast alpha-mating factor: a model for mammalian peptide hormones. Biopolymers 1992; 32:335-9. [PMID: 1623128 DOI: 10.1002/bip.360320407] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Small peptides initiate sexual conjugation in the yeast Saccharomyces cerevisiae and this phenomenon is an ideal paradigm for studying the mode of action of mammalian peptide hormones. 1H-nmr spectroscopy was used to examine the conformation of linear and cyclic analogues of the alpha-factor (WHWLQLKPGQPMY) in aqueous solution. In all cases peptides that exhibit nmr parameters expected for a type II beta-turn have higher biological activities than those that do not appear to assume this conformation. Based on a simple model for the interaction of the pheromone with its receptor, we prepared fragments of the alpha-factor. Several of these fragments either antagonize or potentiate the activity of the alpha-factor. The latter represent the first example of peptide fragments that synergize the activity of the parent pheromone.
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161
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Dayton MT, Faught WE, Becker JM, Burt R. Superior results of ileoanal pull through (IAPT) in polyposis coli vs ulcerative colitis patients. J Surg Res 1992; 52:131-4. [PMID: 1311047 DOI: 10.1016/0022-4804(92)90293-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Colectomy, mucosal proctectomy, and ileoanal pull through (IAPT) have replaced proctocolectomy as the operation of choice in most patients with the colorectal mucosal diseases ulcerative colitis and polyposis coli. This study was conducted to determine whether there is any difference in postoperative morbidity and long-term functional results when IAPT is performed for polyposis coli than when it is performed for ulcerative colitis patients. Between 1982 and 1989, 277 IAPT procedures were performed at the University of Utah Medical Center, 239 for ulcerative colitis and 38 for polyposis coli syndromes. A prospective study compared polyposis and colitis patients after IAPT with regards to age, family history, preoperative findings, operative findings, postoperative complications, and long-term complications. Functional results were compared including day and night stool frequency, incidence of nighttime incontinence, and incidence of pouchitis. The incidence of postoperative complications was lower in the polyposis group than in the colitis group, but the numbers were low enough in both diseases that significant differences were not detected. However, the incidence of pouchitis (0% vs 19%), day (4.2 vs 6.0) and night (0.4 vs 0.9) stool frequency, and nighttime incontinence (5% vs 25%) was significantly lower in the polyposis group when compared to the colitis group. We conclude that IAPT performed for polyposis conditions is associated with superior results when compared with results from patients who undergo the procedure for ulcerative colitis.
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162
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Eriotou-Bargiota E, Xue CB, Naider F, Becker JM. Antagonistic and synergistic peptide analogues of the tridecapeptide mating pheromone of Saccharomyces cerevisiae. Biochemistry 1992; 31:551-7. [PMID: 1310042 DOI: 10.1021/bi00117a036] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Biologically inactive, truncated analogues of the Saccharomyces cerevisiae alpha-mating factor (WHWLQLKPGQPMY) either antagonized or synergized the activity of the native pheromone. An amino-terminal truncated pheromone [WLQLKPGQP(Nle)Y] had no activity by itself, but the analogue acted as an antagonist by competing with binding and activity of the mating factor. In contrast, a carboxyl-terminal truncated pheromone [WHWLQLKPGQP] was not active by itself nor did the peptide compete with alpha-factor for binding to the alpha-factor receptor, but it acted as a synergist by causing a marked increase in the activity of alpha-factor. The observation that residues near the amino terminus may be involved in signal transduction whereas those near the carboxyl terminus influence binding allows us to separate binding and signal transduction in the yeast pheromone response pathway. If found for other hormone-receptor systems, synergists may have potential as therapeutic compounds.
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Zheng H, Zhang HL, Becker JM, Naider F, Farkas WR. The lysine analog L-oxalysine is an inhibitor of RNA synthesis. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1992; 24:145-9. [PMID: 1582527 DOI: 10.1016/0020-711x(92)90240-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. The lysine analog L-4-oxalysine was found to be a potent inhibitor of RNA synthesis in Candida albicans. 2. The compound was a weak inhibitor of protein synthesis and DNA synthesis was not affected. 3. The inhibition of RNA synthesis was reversed by L-lysine but not D-lysine. 4. The decrease in the level of newly synthesized RNA in cells treated with L-oxalysine was due to inhibition of de novo synthesis rather than to degradation of RNA.
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Gounarides JS, Broido MS, Xue CB, Becker JM, Naider FR. The conformation of a-factor is not influenced by the S-prenylation of Cys12. Biochem Biophys Res Commun 1991; 181:1125-30. [PMID: 1764063 DOI: 10.1016/0006-291x(91)92055-o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Two-Dimensional NMR was used to examine the solution conformation of the lipopeptide a-factor, YIIKGVFWDPAC (S-farnesyl) OCH3, from the yeast Saccharomyces cerevisiae and five analogues containing various S-alkylated cysteines in DMSO-d6. NOESY data, NH temperature coefficients, and 3J alpha NH coupling constants indicate that the a-factor is a predominantly unstructured peptide in DMSO. Similar results were obtained for the other peptides indicating that S-prenylation of Cys12 does not affect the conformation of these peptides.
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165
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Island MD, Perry JR, Naider F, Becker JM. Isolation and characterization of S. cerevisiae mutants deficient in amino acid-inducible peptide transport. Curr Genet 1991; 20:457-63. [PMID: 1782673 DOI: 10.1007/bf00334772] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The transport of small peptides into the yeast Saccharomyces cerevisiae is subject to complex regulatory control. In an effort to determine the number, and to address the function, of the components involved in peptide transport and its regulation, spontaneous mutants resistant to toxic di- and tripeptides were isolated under inducing conditions. Twenty-four mutant strains were characterized in detail and fell into two phenotypic groups; one group deficient in amino acid-inducible peptide uptake, the other with a pleiotropic phenotype including a loss of peptide transport. Complementation analysis of recessive mutations in 12 of these strains defined three groups; ptr1 (nine strains), ptr2 (two strains), and ptr3 (one strain). Isolation and screening of 31 additional N-methyl-N-nitro-N-Nitrosoguanidine (MNNG)-induced, peptide transport-deficient mutants produced one ptr3 and 30 ptr2 strains: no additional complementation groups were detected. Uptake of radiolabeled dileucine was negligible in ptr1 and ptr2 strains and was reduced by 65% and 90% in the two ptr3 mutants, indicating that all strains were defective at the transport step. We conclude that the S. cerevisiae amino acid-inducible peptide transport system recognizes a broad spectrum of peptide substrates and involves at least three components. One gene, PTR3, may play an indirect or regulatory role since mutations in this gene cause a pleiotropic phenotype.
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166
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Greenberg BM, Becker JM, Pletcher BA. Congenital bifid sternum: repair in early infancy and literature review. Plast Reconstr Surg 1991; 88:886-9. [PMID: 1924580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Sternal clefting is an unusual congenital anomaly that should be repaired in early infancy. Early surgery is facilitated by a highly compliant bony thorax. The surgical technique is described, including the (1) removal of a wedge at the confluence of the two lateral sternal bands to allow their apposition, (2) intraoperative assessment of pulmonary compliance and central venous pressure, (3) use of bilateral pectoral flaps, and (4) resulting avoidance of major costochondral stair-step osteotomies. The suggested age of repair is 1 to 4 weeks of age.
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167
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Becker JM, McGrath KM, Meagher MP, Parodi JE, Dunnegan DA, Soper NJ. Late functional adaptation after colectomy, mucosal proctectomy, and ileal pouch-anal anastomosis. Surgery 1991; 110:718-24; discussion 725. [PMID: 1925961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Ileal pouch-anal anastomosis (IPAA) is currently an alternative to proctocolectomy and ileostomy for patients with ulcerative colitis or familial polyposis. Some studies have suggested significant anal sphincter damage after mucosal proctectomy. Our aim was to assess prospectively late sphincter function after IPAA. In 250 patients, anorectal pressures were assessed with a pneumohydraulic perfused catheter manometry system. Each patient underwent colectomy, mucosal proctectomy, ileoanal anastomosis of a 15 cm ileal J-pouch, and loop ileostomy. Eight weeks after IPAA, anal manometry was repeated, and the ileostomy was closed. Manometry was repeated at yearly intervals. A decline in resting tone of the anal sphincter occurred early after IPAA with a gradual recovery toward control. External sphincter squeeze after pressures were not affected by IPAA and steadily increased to 8 years after operation. During this time, a progressive increase in J-pouch capacity was noted, and 24-hour stool frequency declined from 7.9 +/- 0.3 stools to 6.5 +/- 0.3 stools (p less than 0.05). We conclude that mucosal proctectomy results in internal anal sphincter trauma but is associated with long-term sphincter recovery, coupled with a significant improvement in external sphincter capacity, ileal pouch volume, and stool frequency.
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Laughon BE, Allaudeen HS, Becker JM, Current WL, Feinberg J, Frenkel JK, Hafner R, Hughes WT, Laughlin CA, Meyers JD. From the National Institutes of Health. Summary of the workshop on future directions in discovery and development of therapeutic agents for opportunistic infections associated with AIDS. J Infect Dis 1991; 164:244-51. [PMID: 1649870 DOI: 10.1093/infdis/164.2.244] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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169
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Marcus S, Caldwell GA, Miller D, Xue CB, Naider F, Becker JM. Significance of C-terminal cysteine modifications to the biological activity of the Saccharomyces cerevisiae a-factor mating pheromone. Mol Cell Biol 1991; 11:3603-12. [PMID: 2046670 PMCID: PMC361107 DOI: 10.1128/mcb.11.7.3603-3612.1991] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have undertaken total synthesis of the Saccharomyces cerevisiae a-factor (NH2-YIIKGVFWDPAC[S-farnesyl]-COOCH3) and several Cys-12 analogs to determine the significance of S-farnesylation and carboxy-terminal methyl esterification to the biological activity of this lipopeptide mating pheromone. Replacement of either the farnesyl group or the carboxy-terminal methyl ester by a hydrogen atom resulted in marked reduction but not total loss of bioactivity as measured by a variety of assays. Moreover, both the farnesyl and methyl ester groups could be replaced by other substituents to produce biologically active analogs. The bioactivity of a-factor decreased as the number of prenyl units on the cysteine sulfur decreased from three to one, and an a-factor analog having the S-farnesyl group replaced by an S-hexadecanyl group was more active than an S-methyl a-factor analog. Thus, with two types of modifications, a-factor activity increased as the S-alkyl group became bulkier and more hydrophobic. MATa cells having deletions of the a-factor structural genes (mfal1 mfa2 mutants) were capable of mating with either sst2 or wild-type MAT alpha cells in the presence of exogenous a-factor, indicating that it is not absolutely essential for MATa cells to actively produce a-factor in order to mate. Various a-factor analogs were found to partially restore mating to these strains as well, and their relative activities in the mating restoration assay were similar to their activities in the other assays used in this study. Mating was not restored by addition of exogenous a-factor to a cross of a wild-type MAT alpha strain and a MATaste6 mutant, indicating a role of the STE6 gene product in mating in addition to its secretion of a-factor.
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170
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Xue CB, Becker JM, Naider F. Synthesis of S-alkyl and C-terminal analogs of the Saccharomyces cerevisiae a-factor. Influence of temperature on the stability of Fmoc and OFm groups toward HF. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1991; 37:476-86. [PMID: 1917304 DOI: 10.1111/j.1399-3011.1991.tb00764.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The a-mating factor of Saccharomyces cerevisiae Tyr-Ile-Ile-Lys-Gly-Val-Phe-Trp-Asp-Pro-Ala-Cys(farnesyl)OCH3, and 10 analogs modified at the cysteine side chain and/or the terminal carboxyl were synthesized using a combination of solid phase and solution phase methodologies. The strategy of synthesis involved the condensation of an amine terminal protected decapeptide with a carboxyl terminal S-alkylated dipeptide ester or amide using benzotriazol-l-yloxy-tris(methylamino)-phosphonium hexafluorophosphate as the coupling agent. The protected decapeptide was assembled on a PAM-resin using 9-fluorenylmethoxycarbonyl (Fmoc) for the protection of the Tyr alpha-amine and Lys epsilon-amine and 9-fluorenylmethyl ester (OFm) for the protection of the Asp beta-carboxyl. Premature loss of the OFm group from the HF cleavage was observed at 0-2 degrees, whereas no loss occurred when the cleavage reaction was conducted at -5 degrees. In contrast to these results, the OFm group in Asp(OFm) was partially removed by HF at -5 degrees and was completely stable to HF only at -20 degrees. The S-alkylated dipeptide esters were prepared, in yields from 64% to 88%, via thioalkylation of amine protected or unprotected dipeptide esters using potassium fluoride dihydrate as the base. The use of a tertiary amine as the base of thiohexadecanylation resulted in low reactivity.
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171
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Tuinman AA, Thomas DA, Cook KD, Xue CB, Naider F, Becker JM. Mass spectrometric signature of S-prenylated cysteine peptides. Anal Biochem 1991; 193:173-7. [PMID: 1872463 DOI: 10.1016/0003-2697(91)90004-d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The fast atom bombardment mass spectra of peptides containing S-prenylated cysteine display signature fragmentations characteristic of this modified amino acid. The fragmentation is independent of the nature of the cysteine carbonyl substituent, easily differentiates prenyl from nonprenyl alkylation, and readily identifies the oligomer count of the prenyl. This screening method, which requires little time, effort, or material (compared with previous analysis methods based on chemical degradation), greatly facilitates the identification of these prenylated proteins.
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172
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Becker JM, Alexander DP. Colectomy, mucosal proctectomy, and ileal pouch-anal anastomosis. A prospective trial of optimal antibiotic management. Ann Surg 1991; 213:242-7. [PMID: 1847796 PMCID: PMC1358335 DOI: 10.1097/00000658-199103000-00011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The ideal prophylactic antibiotic regimen has not been established for patients undergoing colectomy, mucosal proctectomy, and endorectal ileoanal anastomosis, a prolonged operation frequently accompanied by abdominal and pelvic contamination and associated with an infection rate up to 20%. The aim of this study was to evaluate, in a prospective, randomized, double-blind fashion, the efficacy of a short perioperative course compared to an extended postoperative course of intravenous antibiotics (cefoxitin) in patients undergoing colectomy with ileoanal anastomosis. Forty patients with ulcerative colitis or familial polyposis coli received a mechanical and oral antibiotic bowel preparation and a standard three-dose perioperative course of intravenous cefoxitin. Patients then were randomized to receive intravenous cefoxitin, 1 g every 6 hours, or placebo for 5 days. No differences in overall postoperative morbidity were observed and neither group developed intra-abdominal, pelvic, or wound infections. It is concluded that a standard three-dose perioperative course of intravenous antibiotics provides adequate prophylaxis in the prevention of infectious complications in patients undergoing colectomy, mucosal proctectomy, and ileoanal anastomosis.
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173
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Brooks DC, Becker JM, Carr-Locke DL. Laparoscopic cholecystectomy. BAILLIERE'S CLINICAL GASTROENTEROLOGY 1991; 5:225-38. [PMID: 1830229 DOI: 10.1016/0950-3528(91)90014-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Laparoscopic cholecystectomy has emerged in the last 2 years as a unique procedure that offers the long-term advantages of open cholecystectomy without much of the short-term morbidity. Importantly, when compared with non-surgical approaches to symptomatic gallstones, it is suitable for virtually all patients rather than a highly-selected group as in the case of oral bile salt dissolution therapy or extracorporeal lithotripsy. Furthermore, it obviates the high recurrence rate seen with these techniques. Complications including bleeding and ductal injury appear to occur at a slightly higher rate than with traditional open cholecystectomy, but most surgeons who have had experience with the procedure predict that these complications will become rarer as more experience is gained. We may indeed be witnessing the first major successful challenge to traditional surgical management of symptomatic gallstone disease in 100 years.
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Krainer E, Becker JM, Naider F. Synthesis and biological evaluation of dipeptidyl and tripeptidyl polyoxin and nikkomycin analogues as anticandidal prodrugs. J Med Chem 1991; 34:174-80. [PMID: 1992114 DOI: 10.1021/jm00105a026] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Nine analogues (1-5, 9-12) of the peptidyl nucleoside antibiotics nikkomycin and polyoxin were synthesized and tested for their biological properties against different strains of the pathogenic yeast Candida albicans. The tripeptidyl series of analogues (1-5) was designed to behave as prodrugs, releasing a toxic moiety upon enzymatic hydrolysis inside the cell. The dipeptidyl series (9-12) was designed as double-targeted drugs, being themselves toxic and releasing a toxic amino acid upon hydrolysis. All the analogues were prepared by coupling suitably protected amino acid p-nitrophenyl esters to 1-(5'-amino-5'-deoxy-alpha-D-allofuranuronosyl)uracil (UPOC) or the corresponding polyoxins and nikkomycins, with subsequent removal of the protecting group. Improved coupling yields were observed when DMSO was used as the solvent. Products were purified with use of reversed-phase HPLC and, in one case, diastereomeric products (compound 11) were resolved by using this procedure. One of the tripeptidyl nikkomycins behaved as a prodrug but none of the compounds, as measured by in vitro testing, proved more effective than nikkomycin as an anticandidal agent.
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175
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Marcus S, Caldwell GA, Xue CB, Naider F, Becker JM. Total in vitro maturation of the Saccharomyces cerevisiae a-factor lipopeptide mating pheromone. Biochem Biophys Res Commun 1990; 172:1310-6. [PMID: 2244913 DOI: 10.1016/0006-291x(90)91592-g] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The a-factor mating pheromone, produced by Saccharomyces cerevisiae a haploid cells, is post-translationally modified in a manner analogous to that of the ras proto-oncogene product. A consensus C-terminal amino acid sequence, -CAAX (C is cysteine, A is aliphatic amino acid, and X is any amino acid), is the target of these modifications, which include isoprenylation (essential for Ras function), proteolysis of the -AAX sequence, and carboxy methyl esterification. Recently, the RAM/DPR1 gene product was shown to be a component of the activity responsible for isoprenylation of both Ras and a-factor. In this report, we present an in vitro assay which not only detects a-factor isoprenylation, but also proteolysis and carboxy methyl esterification, and directly demonstrates, biochemically, the order of these processing events. This a-factor maturation assay may prove useful for screening agents which block any of the steps involved in the post-translational modification of the a-factor and Ras -CAAX sequences. Such agents would be potential anti-Ras-related cancer therapeutic drugs.
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