D-Glutamic acid is an essential component of bacterial cell wall peptidoglycan in both gram-posit... more D-Glutamic acid is an essential component of bacterial cell wall peptidoglycan in both gram-positive and gram-negative bacteria. Very little is known concerning the genetics and biochemistry of D-glutamate production in most bacteria, including Escherichia coli. Evidence is presented in this report for the roles of two distinct genes in E. coli WM335, a strain which is auxotrophic for D-glutamate. The first gene, which restores D-glutamate independence in WM335, was mapped, cloned, and sequenced. This gene, designated dga, is a previously reported open reading frame, located at 89.8 min on the E. coli map. The second gene, giS, is located at 82 min. gitS encodes a protein that is involved in the transport of D-and L-glutamic acid into E. cofl, and the gitS gene of WM335 was found to contain two missense mutations. To construct D-glutamate auxotrophs, it is necessary to transfer sequentially the mutated gitS locus, and then the mutated dga locus into the recipient. The sequences of the mutant forms of both dga and gitS are also presented. 1221.
The gene required for methicillin resistance in staphylococci, mecA, encodes the low-affinity pen... more The gene required for methicillin resistance in staphylococci, mecA, encodes the low-affinity penicillin-binding protein 2a (PBP2a). Transcriptional regulation of mecA is accomplished in some isolates by mecR1 and mecI, cotranscribed chromosomal genes that encode a putative signal transducer and a transcriptional repressor, respectively. Two Staphylococcus aureus strains that have identical mecR1-mecI nucleotide sequences, BMS1 and N315P, both exhibit low-level, heterotypic expression of methicillin resistance and contain no beta-lactamase coregulatory sequences. mecR1-mecI was amplified from BMS1 by PCR and was shown to be functional on a high-copy-number plasmid when introduced into an S. aureus strain with a deleted mecR1-mecI locus. Cloned mecR1-mecI repressed phenotypic expression of methicillin resistance, mecA transcription and PBP2a production and mediated PBP2a induction in response to certain beta-lactam antibiotics. However, mecR1-mecI had different regulatory activities ...
The activities of several tricyclic heteroaryl isothiazolones (HITZs) against an assortment of gr... more The activities of several tricyclic heteroaryl isothiazolones (HITZs) against an assortment of gram-positive and gram-negative clinical isolates were assessed. These compounds target bacterial DNA replication and were found to possess broad-spectrum activities especially against gram-positive strains, including antibiotic- resistant staphylococci and streptococci. These included methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-nonsusceptible staphylococci, and quinolone-resistant strains. The HITZs were more active than the
Laparoscopic resection is rapidly becoming the treatment of choice for small- to medium-sized gas... more Laparoscopic resection is rapidly becoming the treatment of choice for small- to medium-sized gastric gastrointestinal stromal tumors (GIST). While long-term oncologic data are available, quality of life outcomes are less known. Our IRB-approved prospectively maintained database was retrospectively queried (2003-2013) for patients who underwent laparoscopic gastric GIST resection. Demographics along with perioperative and oncologic outcomes were collected and analyzed. Patients were contacted and asked to complete a quality of life survey consisting of Likert scales scored from 1 to 5. Patients also completed the Gastrointestinal Quality of Life Index (GIQLI). A total of 69 patients were identified and 36 patients (59.0 % of eligible patients) responded to the survey. Median follow-up was 39 months. Patients most commonly reported no change in weight, appetite, early satiety, heartburn, persistent cough, dysphagia, and reflux medication dosing postoperatively. The median scores for chest pain and regurgitation were 4, falling in the "worsened" range. 8.33 % of patients reported worsened chest pain and 11.11 % of patients reported worsened regurgitation postoperatively. The GIQLI scores had a mean of 126.9 (range 77-141). While some patients reported a worsening in early satiety, most patients reported no change in symptoms postoperatively, and the GIQLI scores remained within the normal range. Laparoscopic resection of gastric GIST provides durable results with minimal effect on longer-term quality of life.
Introduction: Minimally Invasive Esophagectomy (MIE) is increasingly utilized for the treatment o... more Introduction: Minimally Invasive Esophagectomy (MIE) is increasingly utilized for the treatment of esophageal and gastroesophageal junction (GEJ) malignancies; however, perioperative morbidity remains significant. We sought to compare the severity of complications between patients undergoing MIE and Open/Hybrid Esophagectomy (OHE). Methods: Our single institution IRB-approved prospectively maintained database was retrospectively queried and a contemporary series of patients who underwent MIE (2008-2013) was compared to a cohort undergoing OHE – Mckeown approach (39), Ivor Lewis approach (16), Hybrid (13) (2000-2013). Hybrid esophagectomy was defined as having one component of the surgery performed minimally invasively—either thoracoscopic or laparoscopic. Perioperative complications were graded using the Clavien-Dindo classification. Statistical analysis was performed using two-tailed t-test and Fisher exact test to assess the impact of operative approach (MIE vs. OHE) on operative ...
Key enzymes that assemble the bacterial cell wall are also the target of the Beta-lactam class of... more Key enzymes that assemble the bacterial cell wall are also the target of the Beta-lactam class of antibiotics. The covalent binding of labeled penicillin to these proteins has been used in numerous studies in drug discovery, antibiotic mechanisms of action and resistance, and cell wall physiology. Methods to label and measure penicillin binding proteins in two prototypical organisms, a Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus), are described. The methods discussed include identifying penicillin-binding proteins in both intact cells (in vivo measurements) and isolated cell membranes.
We synthesized a diverse series of 9H-isothiazolo[5,4-b]quinoline-3,4-diones containing heteroaro... more We synthesized a diverse series of 9H-isothiazolo[5,4-b]quinoline-3,4-diones containing heteroaromatic groups at the 7-position via palladium-catalyzed cross-coupling. Many of these compounds demonstrated potent antistaphylococcal activity (MICs 2 microg/mL) against a multi-drug-resistant strain (ATCC 700699) and low cytotoxic activity (CC(50)>100 microM) against the human cell line Hep2 (laryngeal carcinoma).
The biochemical properties of the D-glutamate-adding enzymes (MurD) from Escherichia coli, Haemop... more The biochemical properties of the D-glutamate-adding enzymes (MurD) from Escherichia coli, Haemophilus influenzae, Enterococcus faecalis, and Staphylococcus aureus were investigated to detect any differences in the activity of this enzyme between gram-positive and gram-negative bacteria. The genes (murD) that encode these enzymes were cloned into pMAL-c2 fusion vector and overexpressed as maltose-binding protein-MurD fusion proteins. Each fusion protein was purified to homogeneity by affinity to amylose resin. Proteolytic treatments of the fusion proteins with factor Xa regenerated the individual MurD proteins. It was found that these fusion proteins retain D-glutamate-adding activity and have Km and Vmax values similar to those of the regenerated MurDs, except for the H. influenzae enzyme. Substrate inhibition by UDP-N-acetylmuramyl-L-alanine, the acceptor substrate, was observed at concentrations greater than 15 and 30 microM for E. coli and H. influenzae MurD, respectively. Such ...
Pancreatic fistula (PF) is a significant cause of morbidity in patients undergoing distal pancrea... more Pancreatic fistula (PF) is a significant cause of morbidity in patients undergoing distal pancreatectomy (DP), with an incidence of 15-40%. It remains unclear if the location of pancreatic transection affects the rate of PF occurrence. This study examines the correlation between the transection site of the pancreas during DP and the incidence of PF. All cases of DP from October 2005 to January 2012 were reviewed retrospectively from an institutional review board-approved database at the Thomas Jefferson University Hospital. Patient demographics and perioperative outcomes were analyzed. The pancreatic transection location was determined by review of operative reports, and then dichotomized into 2 groups: neck/body or tail. PF were graded following the International Study Group on Pancreatic Fistula guidelines. During the study period, 294 DP were performed with 244 pancreas transections at the neck/body and 50 at the tail. Of the 294 patients, 52 (17.7%) developed a postoperative PF. The incidence of PF after transection at the tail of the pancreas was higher (28%) when compared with transection at the neck/body (15.6%; P = .04). When stratified by PF grade, grade A PF occurred more commonly when transection of the gland was at the tail (22% tail vs 8.2% neck/body; P = .007); however, no difference was found for grade B/C PF (6% tail vs 7.4% neck/body; P = 1). Our data suggest that PF occurs more often when the tail is transected during DP, although the majority are low grade and of minimal clinical significance. More severe PF occurred equally between the transection sites.
Clusters of peptidoglycan biosynthesis and cell division genes (DCW genes) were identified and se... more Clusters of peptidoglycan biosynthesis and cell division genes (DCW genes) were identified and sequenced in two gram-positive cocci, Staphylococcus aureus and Enterococcus faecalis. The results indicated some similarities in organization compared with previously reported bacterial DCW gene clusters, including the presence of penicillin-binding proteins at the left ends and ftsA and ftsZ cell division genes at the right ends of the clusters. However, there were also some important differences, including the absence of several genes, the comparative sizes of the div1B and ftsQ genes, and a wide range of amino acid sequence similarities when the genes of the gram-positive cocci were translated and compared to bacterial homologs.
Two D-glutamic acid biosynthetic activities, glutamate racemase and D-amino acid transaminase, ha... more Two D-glutamic acid biosynthetic activities, glutamate racemase and D-amino acid transaminase, have been described previously for bacteria. To date, no bacterial species has been reported to possess both activities. Genetic complementation studies using Escherichia coli WM335, a D-glutamic acid auxotroph, and cloned chromosomal DNA fragments from Staphylococcus haemolyticus revealed two distinct DNA fragments containing open reading frames which, when present, allowed growth on medium without exogenous D-glutamic acid. Amino acid sequences of the two open reading frames derived from the DNA nucleotide sequences indicated extensive identity with the amino acid sequence of Pediococcus pentosaceous glutamate racemase in one case and with that of the D-amino acid transaminase of Bacillus spp. in the second case. Enzymatic assays of lysates of E. coli WM335 strains containing either the cloned staphylococcal racemase or transminase verified the identities of these activities. Subsequent ...
Bacterial" Genes-to-Screens" in the Post-Genomic Era Michael J. Pucci, John F. Barrett,... more Bacterial" Genes-to-Screens" in the Post-Genomic Era Michael J. Pucci, John F. Barrett, and Thomas J. Dougherty INTRODUCTION In ... 23. Kotra LP, Vakulenko S. Mobashery S. From genes to sequences to antibiotics: prospects for future developments from microbial genomics. ...
Antimicrobial agents and chemotherapy, Jan 12, 2015
In a loss of viability screen using small molecules against methicillin resistant S. aureus MRSA ... more In a loss of viability screen using small molecules against methicillin resistant S. aureus MRSA USA300 with sub-MIC β-lactam, we found a small molecule, designated as DNAC-1, that potentiated the effect of oxacillin (MIC of oxacillin decreased from 64 to 0.25 μg/ml). Fluorescence microscopy indicated disruption of membrane structures within 15 minutes of exposure to DNAC-1 at 2x MIC. This permeabilization was accompanied by a rapid loss of membrane potential, as monitored by the DiOC2 dye. Macromolecular analysis showed inhibition of staphylococcal cell wall synthesis by DNAC-1. Transmission electron microscopy of treated MRSA USA300 cells revealed a slightly thicker cell wall together with mesosome -like projections into the cytosol. Exposure of USA300 cells to DNAC-1 was associated with mislocalization of FtsZ accompanied by localization of PBP2 and PBP4 away from the septum as well as mild activation of the vraRS-mediated cell-wall stress response. However, DNAC-1 does not have ...
Background. Antiplatelet therapy with aspirin is prevalent among patients presenting for operativ... more Background. Antiplatelet therapy with aspirin is prevalent among patients presenting for operative treatment of pancreatic disorders. Operative practice has called for the cessation of aspirin 7-10 days before elective procedures because of the perceived increased risk of procedure-related bleeding. Our practice at Thomas Jefferson University has been to continue aspirin therapy throughout the perioperative period in patients undergoing elective pancreatic surgery. Study design. Records for patients undergoing pancreatoduodenectomy, distal pancreatectomy, or total pancreatectomy between October 2005 and February 2012 were queried for perioperative aspirin use in this institutional research boardÀapproved retrospective study. Statistical analyses were performed with Stata software. Results. During the study period, 1,017 patients underwent pancreatic resection, of whom 289 patients (28.4%) were maintained on aspirin through the morning of the operation. Patients in the aspirin group were older than those not taking aspirin (median 69 years vs 62 years, P < .0001). The estimated intraoperative blood loss was similar between the two groups, aspirin versus no aspirin (median 400 mL vs 400 mL, P = .661), as was the rate of blood transfusion anytime during the index admission (29% vs 26%, P = 0.37) and the postoperative duration of hospital stay (median 7 days vs 6 days, P = .103). The aspirin group had a slightly increased rate of cardiovascular complications (10.1% vs 7.0%, P = .107), likely reflecting their increased cardiovascular comorbidities that led to their physicians recommending aspirin therapy. Rates of pancreatic fistula (15.1% vs 13.5%, P = .490) and hospital readmissions were similar (16.9% vs 14.9%, P = .451).
The Pediococcus pentosaceus glutamate racemase gene product complemented the D-glutamate auxotrop... more The Pediococcus pentosaceus glutamate racemase gene product complemented the D-glutamate auxotrophy of Escherichia coli WM335. Amino acid sequence analysis of the two proteins revealed 28% identity, primarily in six clusters scattered throughout the sequence. Further analyses indicated secondary structure similarities between the two proteins. These data support a recent report that the dga (murl) gene product is a glutamate racemase.
D-Glutamic acid is an essential component of bacterial cell wall peptidoglycan in both gram-posit... more D-Glutamic acid is an essential component of bacterial cell wall peptidoglycan in both gram-positive and gram-negative bacteria. Very little is known concerning the genetics and biochemistry of D-glutamate production in most bacteria, including Escherichia coli. Evidence is presented in this report for the roles of two distinct genes in E. coli WM335, a strain which is auxotrophic for D-glutamate. The first gene, which restores D-glutamate independence in WM335, was mapped, cloned, and sequenced. This gene, designated dga, is a previously reported open reading frame, located at 89.8 min on the E. coli map. The second gene, giS, is located at 82 min. gitS encodes a protein that is involved in the transport of D-and L-glutamic acid into E. cofl, and the gitS gene of WM335 was found to contain two missense mutations. To construct D-glutamate auxotrophs, it is necessary to transfer sequentially the mutated gitS locus, and then the mutated dga locus into the recipient. The sequences of the mutant forms of both dga and gitS are also presented. 1221.
The gene required for methicillin resistance in staphylococci, mecA, encodes the low-affinity pen... more The gene required for methicillin resistance in staphylococci, mecA, encodes the low-affinity penicillin-binding protein 2a (PBP2a). Transcriptional regulation of mecA is accomplished in some isolates by mecR1 and mecI, cotranscribed chromosomal genes that encode a putative signal transducer and a transcriptional repressor, respectively. Two Staphylococcus aureus strains that have identical mecR1-mecI nucleotide sequences, BMS1 and N315P, both exhibit low-level, heterotypic expression of methicillin resistance and contain no beta-lactamase coregulatory sequences. mecR1-mecI was amplified from BMS1 by PCR and was shown to be functional on a high-copy-number plasmid when introduced into an S. aureus strain with a deleted mecR1-mecI locus. Cloned mecR1-mecI repressed phenotypic expression of methicillin resistance, mecA transcription and PBP2a production and mediated PBP2a induction in response to certain beta-lactam antibiotics. However, mecR1-mecI had different regulatory activities ...
The activities of several tricyclic heteroaryl isothiazolones (HITZs) against an assortment of gr... more The activities of several tricyclic heteroaryl isothiazolones (HITZs) against an assortment of gram-positive and gram-negative clinical isolates were assessed. These compounds target bacterial DNA replication and were found to possess broad-spectrum activities especially against gram-positive strains, including antibiotic- resistant staphylococci and streptococci. These included methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-nonsusceptible staphylococci, and quinolone-resistant strains. The HITZs were more active than the
Laparoscopic resection is rapidly becoming the treatment of choice for small- to medium-sized gas... more Laparoscopic resection is rapidly becoming the treatment of choice for small- to medium-sized gastric gastrointestinal stromal tumors (GIST). While long-term oncologic data are available, quality of life outcomes are less known. Our IRB-approved prospectively maintained database was retrospectively queried (2003-2013) for patients who underwent laparoscopic gastric GIST resection. Demographics along with perioperative and oncologic outcomes were collected and analyzed. Patients were contacted and asked to complete a quality of life survey consisting of Likert scales scored from 1 to 5. Patients also completed the Gastrointestinal Quality of Life Index (GIQLI). A total of 69 patients were identified and 36 patients (59.0 % of eligible patients) responded to the survey. Median follow-up was 39 months. Patients most commonly reported no change in weight, appetite, early satiety, heartburn, persistent cough, dysphagia, and reflux medication dosing postoperatively. The median scores for chest pain and regurgitation were 4, falling in the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;worsened&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; range. 8.33 % of patients reported worsened chest pain and 11.11 % of patients reported worsened regurgitation postoperatively. The GIQLI scores had a mean of 126.9 (range 77-141). While some patients reported a worsening in early satiety, most patients reported no change in symptoms postoperatively, and the GIQLI scores remained within the normal range. Laparoscopic resection of gastric GIST provides durable results with minimal effect on longer-term quality of life.
Introduction: Minimally Invasive Esophagectomy (MIE) is increasingly utilized for the treatment o... more Introduction: Minimally Invasive Esophagectomy (MIE) is increasingly utilized for the treatment of esophageal and gastroesophageal junction (GEJ) malignancies; however, perioperative morbidity remains significant. We sought to compare the severity of complications between patients undergoing MIE and Open/Hybrid Esophagectomy (OHE). Methods: Our single institution IRB-approved prospectively maintained database was retrospectively queried and a contemporary series of patients who underwent MIE (2008-2013) was compared to a cohort undergoing OHE – Mckeown approach (39), Ivor Lewis approach (16), Hybrid (13) (2000-2013). Hybrid esophagectomy was defined as having one component of the surgery performed minimally invasively—either thoracoscopic or laparoscopic. Perioperative complications were graded using the Clavien-Dindo classification. Statistical analysis was performed using two-tailed t-test and Fisher exact test to assess the impact of operative approach (MIE vs. OHE) on operative ...
Key enzymes that assemble the bacterial cell wall are also the target of the Beta-lactam class of... more Key enzymes that assemble the bacterial cell wall are also the target of the Beta-lactam class of antibiotics. The covalent binding of labeled penicillin to these proteins has been used in numerous studies in drug discovery, antibiotic mechanisms of action and resistance, and cell wall physiology. Methods to label and measure penicillin binding proteins in two prototypical organisms, a Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus), are described. The methods discussed include identifying penicillin-binding proteins in both intact cells (in vivo measurements) and isolated cell membranes.
We synthesized a diverse series of 9H-isothiazolo[5,4-b]quinoline-3,4-diones containing heteroaro... more We synthesized a diverse series of 9H-isothiazolo[5,4-b]quinoline-3,4-diones containing heteroaromatic groups at the 7-position via palladium-catalyzed cross-coupling. Many of these compounds demonstrated potent antistaphylococcal activity (MICs 2 microg/mL) against a multi-drug-resistant strain (ATCC 700699) and low cytotoxic activity (CC(50)>100 microM) against the human cell line Hep2 (laryngeal carcinoma).
The biochemical properties of the D-glutamate-adding enzymes (MurD) from Escherichia coli, Haemop... more The biochemical properties of the D-glutamate-adding enzymes (MurD) from Escherichia coli, Haemophilus influenzae, Enterococcus faecalis, and Staphylococcus aureus were investigated to detect any differences in the activity of this enzyme between gram-positive and gram-negative bacteria. The genes (murD) that encode these enzymes were cloned into pMAL-c2 fusion vector and overexpressed as maltose-binding protein-MurD fusion proteins. Each fusion protein was purified to homogeneity by affinity to amylose resin. Proteolytic treatments of the fusion proteins with factor Xa regenerated the individual MurD proteins. It was found that these fusion proteins retain D-glutamate-adding activity and have Km and Vmax values similar to those of the regenerated MurDs, except for the H. influenzae enzyme. Substrate inhibition by UDP-N-acetylmuramyl-L-alanine, the acceptor substrate, was observed at concentrations greater than 15 and 30 microM for E. coli and H. influenzae MurD, respectively. Such ...
Pancreatic fistula (PF) is a significant cause of morbidity in patients undergoing distal pancrea... more Pancreatic fistula (PF) is a significant cause of morbidity in patients undergoing distal pancreatectomy (DP), with an incidence of 15-40%. It remains unclear if the location of pancreatic transection affects the rate of PF occurrence. This study examines the correlation between the transection site of the pancreas during DP and the incidence of PF. All cases of DP from October 2005 to January 2012 were reviewed retrospectively from an institutional review board-approved database at the Thomas Jefferson University Hospital. Patient demographics and perioperative outcomes were analyzed. The pancreatic transection location was determined by review of operative reports, and then dichotomized into 2 groups: neck/body or tail. PF were graded following the International Study Group on Pancreatic Fistula guidelines. During the study period, 294 DP were performed with 244 pancreas transections at the neck/body and 50 at the tail. Of the 294 patients, 52 (17.7%) developed a postoperative PF. The incidence of PF after transection at the tail of the pancreas was higher (28%) when compared with transection at the neck/body (15.6%; P = .04). When stratified by PF grade, grade A PF occurred more commonly when transection of the gland was at the tail (22% tail vs 8.2% neck/body; P = .007); however, no difference was found for grade B/C PF (6% tail vs 7.4% neck/body; P = 1). Our data suggest that PF occurs more often when the tail is transected during DP, although the majority are low grade and of minimal clinical significance. More severe PF occurred equally between the transection sites.
Clusters of peptidoglycan biosynthesis and cell division genes (DCW genes) were identified and se... more Clusters of peptidoglycan biosynthesis and cell division genes (DCW genes) were identified and sequenced in two gram-positive cocci, Staphylococcus aureus and Enterococcus faecalis. The results indicated some similarities in organization compared with previously reported bacterial DCW gene clusters, including the presence of penicillin-binding proteins at the left ends and ftsA and ftsZ cell division genes at the right ends of the clusters. However, there were also some important differences, including the absence of several genes, the comparative sizes of the div1B and ftsQ genes, and a wide range of amino acid sequence similarities when the genes of the gram-positive cocci were translated and compared to bacterial homologs.
Two D-glutamic acid biosynthetic activities, glutamate racemase and D-amino acid transaminase, ha... more Two D-glutamic acid biosynthetic activities, glutamate racemase and D-amino acid transaminase, have been described previously for bacteria. To date, no bacterial species has been reported to possess both activities. Genetic complementation studies using Escherichia coli WM335, a D-glutamic acid auxotroph, and cloned chromosomal DNA fragments from Staphylococcus haemolyticus revealed two distinct DNA fragments containing open reading frames which, when present, allowed growth on medium without exogenous D-glutamic acid. Amino acid sequences of the two open reading frames derived from the DNA nucleotide sequences indicated extensive identity with the amino acid sequence of Pediococcus pentosaceous glutamate racemase in one case and with that of the D-amino acid transaminase of Bacillus spp. in the second case. Enzymatic assays of lysates of E. coli WM335 strains containing either the cloned staphylococcal racemase or transminase verified the identities of these activities. Subsequent ...
Bacterial" Genes-to-Screens" in the Post-Genomic Era Michael J. Pucci, John F. Barrett,... more Bacterial" Genes-to-Screens" in the Post-Genomic Era Michael J. Pucci, John F. Barrett, and Thomas J. Dougherty INTRODUCTION In ... 23. Kotra LP, Vakulenko S. Mobashery S. From genes to sequences to antibiotics: prospects for future developments from microbial genomics. ...
Antimicrobial agents and chemotherapy, Jan 12, 2015
In a loss of viability screen using small molecules against methicillin resistant S. aureus MRSA ... more In a loss of viability screen using small molecules against methicillin resistant S. aureus MRSA USA300 with sub-MIC β-lactam, we found a small molecule, designated as DNAC-1, that potentiated the effect of oxacillin (MIC of oxacillin decreased from 64 to 0.25 μg/ml). Fluorescence microscopy indicated disruption of membrane structures within 15 minutes of exposure to DNAC-1 at 2x MIC. This permeabilization was accompanied by a rapid loss of membrane potential, as monitored by the DiOC2 dye. Macromolecular analysis showed inhibition of staphylococcal cell wall synthesis by DNAC-1. Transmission electron microscopy of treated MRSA USA300 cells revealed a slightly thicker cell wall together with mesosome -like projections into the cytosol. Exposure of USA300 cells to DNAC-1 was associated with mislocalization of FtsZ accompanied by localization of PBP2 and PBP4 away from the septum as well as mild activation of the vraRS-mediated cell-wall stress response. However, DNAC-1 does not have ...
Background. Antiplatelet therapy with aspirin is prevalent among patients presenting for operativ... more Background. Antiplatelet therapy with aspirin is prevalent among patients presenting for operative treatment of pancreatic disorders. Operative practice has called for the cessation of aspirin 7-10 days before elective procedures because of the perceived increased risk of procedure-related bleeding. Our practice at Thomas Jefferson University has been to continue aspirin therapy throughout the perioperative period in patients undergoing elective pancreatic surgery. Study design. Records for patients undergoing pancreatoduodenectomy, distal pancreatectomy, or total pancreatectomy between October 2005 and February 2012 were queried for perioperative aspirin use in this institutional research boardÀapproved retrospective study. Statistical analyses were performed with Stata software. Results. During the study period, 1,017 patients underwent pancreatic resection, of whom 289 patients (28.4%) were maintained on aspirin through the morning of the operation. Patients in the aspirin group were older than those not taking aspirin (median 69 years vs 62 years, P < .0001). The estimated intraoperative blood loss was similar between the two groups, aspirin versus no aspirin (median 400 mL vs 400 mL, P = .661), as was the rate of blood transfusion anytime during the index admission (29% vs 26%, P = 0.37) and the postoperative duration of hospital stay (median 7 days vs 6 days, P = .103). The aspirin group had a slightly increased rate of cardiovascular complications (10.1% vs 7.0%, P = .107), likely reflecting their increased cardiovascular comorbidities that led to their physicians recommending aspirin therapy. Rates of pancreatic fistula (15.1% vs 13.5%, P = .490) and hospital readmissions were similar (16.9% vs 14.9%, P = .451).
The Pediococcus pentosaceus glutamate racemase gene product complemented the D-glutamate auxotrop... more The Pediococcus pentosaceus glutamate racemase gene product complemented the D-glutamate auxotrophy of Escherichia coli WM335. Amino acid sequence analysis of the two proteins revealed 28% identity, primarily in six clusters scattered throughout the sequence. Further analyses indicated secondary structure similarities between the two proteins. These data support a recent report that the dga (murl) gene product is a glutamate racemase.
Uploads
Papers by Michael Pucci