PU.1-mediated transcription is enhanced by HMG-I(Y)-dependent structural mechanisms.

The ets transcription factor PU.1 is an important regulator of the immunoglobulin heavy chain gene intronic enhancer, or mu enhancer. However, PU.1 is only one component of the large multiprotein complex required for B cell-specific enhancer activation. The transcriptional coactivator HMG-I(Y), a protein demonstrated to physically interact with PU.1, increases PU.1 affinity for the mu enhancer muB element, indicating that HMG-I(Y) may play a role in the transcriptionally active mu enhanceosome. Increased PU.1 affinity is not mediated by HMG-I(Y)-induced changes in DNA structure. Investigation of alternative mechanisms to explain the HMG-I(Y)-mediated increase in PU.1/mu enhancer binding demonstrated, by trypsin and chymotrypsin mapping, that interaction between PU.1 and HMG-I(Y) in solution induces a structural change in PU.1. In the presence of HMG-I(Y) and wild-type mu enhancer DNA, PU.1 becomes more chymotrypsin resistant, suggesting an additional change in PU.1 structure upon HMG-I(Y)-induced PU.1/DNA binding. From these results, we suggest that increased DNA affinity under limiting PU.1 concentrations is mediated by an HMG-I(Y)-induced structural change in PU.1. In functional assays, HMG-I(Y) further augments transcriptional synergy between PU.1 and another member of the ets family, Ets-1, indicating that HMG-I(Y) is a functional component of the active enhancer complex. These studies suggest a new mechanism for HMG-I(Y)-mediated coactivation; HMG-I(Y) forms protein-protein interactions with a transcription factor, which alters the three-dimensional structure of the factor, resulting in enhanced DNA binding and transcriptional activation. This mechanism may be important for transcriptional activation under conditions of limiting transcription factor concentration, such as at the low levels of PU.1 expressed in B cells.

Soft tissue infections.

Soft tissue infections vary widely in their nature and severity, and their nomenclature is confusing. A clear approach to management must allow rapid identification and treatment of the diffuse necrotizing infections because they are life-threatening. This review classifies soft tissue infections by their degree of localization and the presence of tissue necrosis. Most focal nonnecrotizing infections start in the skin or adnexae and are easily recognized and readily treated by local measures. Patients with cellulitis, the commonest diffuse nonnecrotizing infection, should be stratified from mild to severe and complicated and then treated with oral or systemic antibiotics. Focal necrotizing infections are relatively uncommon, but they are readily diagnosed on sight and effectively managed by local debridement and systemic antibiotics. In contrast, diffuse necrotizing infections may masquerade in many forms, delaying diagnosis and treatment. Edema out of proportion to erythema, subcutaneous gas, and skin vesicles are important markers. Aggressive sequential debridement and broad-spectrum intravenous antibiotics revised after 48 hours provide the best strategy for management.

Serine derived NK1 antagonists. 1: The effect of modifications to the serine substituents.

A series of novel serine derived NK1 antagonists is described. The effect of variations in the N-benzyl, O-benzyl and serine groups are used to define the elements which are necessary for binding.

Should antibiotic prophylaxis be used routinely in clean surgical procedures: a tentative yes.

BACKGROUND: The incidence of surgical site infection (SSI) after clean surgical procedure has traditionally been regarded as too low for routine antibiotic prophylaxis. But we now know that host factors may increase the risk of SSI to as high as 20%. We assessed the value of prophylactic cefotaxime in patients stratified for risk of SSI in a randomized double-blind trial. METHODS: Patients admitted for clean elective operations were enrolled, stratified for risk by National Nosocomial Infection Survey criteria, and randomized to receive intravenous cefotaxime 2 gm or placebo on call for operation. They were followed for 4 to 6 weeks for SSI diagnosed by Centers for Disease Control and Prevention criteria. RESULTS: Analysis of 775 patients showed that the 378 evaluable patients who received cefotaxime had 70% fewer SSI than those who did not--Mantel-Haenszel risk ratio (MH-RR) 0.31; 95% confidence intervals (CI) 0.11 to 0.83. Benefit was clear in the 616 low risk patients--0.97% versus 3.9% SSI (MH-RR 0.25, CI 0.07 to 0.87, p = 0.018), but only a trend was seen in 136 high risk patients--2.8% versus 6.1% SSI (MH-RR 0.48, CI 0.09 to 2.5). CONCLUSIONS: The results indicate clear benefit for routine antibiotic prophylaxis in clean surgical procedures. High risk patients need more study.

Tryptophan-derived NK1 antagonists: conformationally constrained heterocyclic bioisosteres of the ester linkage.

The 3,5-bis(trifluoromethyl)benzyl ester of N-acetyl-L-tryptophan 1 (L-732,138) has been identified previously as a potent and selective substance P receptor antagonist. A series of analogs which introduced a 6-membered heterocyclic ring into the backbone of this structure were prepared for evaluation as bioisosteric replacements of the ester linkage of 1. The 2,5-dioxopiperazine 2 had very weak receptor affinity, but 2-oxopiperazine 5 exhibited modest activity. Examination of the conformations accessible to the substituents on these templates led to exploration of the corresponding 5-membered heterocyclic rings. This study culminated in the identification of oxazolidinedione 14 as a suitable ester mimic in terms of the retention of good NK1 binding affinity.

Synthesis and biological evaluation of NK1 antagonists derived from L-tryptophan.

The 3,5-bis(trifluoromethyl)benzyl ester of N-acetyl-L-tryptophan (3), which was derived from the screening lead N-ethyl-L-tryptophan benzyl ester, has been used as a starting point to identify high-affinity substance P receptor antagonists with improved in vivo activity. Altering the ester moiety to an amide or ether led to a substantial loss in binding affinity, but conversion to a ketone provided compounds with affinity comparable to the equivalent esters. A homochiral synthesis of the key intermediate amino ketone 15 was developed which allows its preparation on a large scale. From this intermediate a range of amine-containing acylamino derivatives were prepared with affinity optimized in the morpholinylbutyramide 161 which has an IC50 of 0.17 nM at the human NK1 receptor. In addition to improving affinity, the amino group also provided aqueous solubility for a number of these derivatives. When tested in vivo the quinuclidine derivative L-737,488 (16i) was found to be an orally active (ID50 = 1.8 mg/kg) inhibitor of substance P-induced dermal extravasation in the guinea pig.

Comparison of single-dose cefotetan and multidose cefoxitin as intravenous prophylaxis in elective, open biliary tract surgery: a multicentre, double-blind, randomized study.

OBJECTIVE: To compare the safety, tolerance and prophylactic effectiveness of a single 2-g dose of cefotetan with a standard prophylactic regimen of cefoxitin in reducing the incidence of postoperative infections after elective, open biliary tract surgery. DESIGN: Multicentre, double-blind, randomized comparative study with a 4-week follow-up. SETTING: Five Canadian university centres. PARTICIPANTS: One hundred and eleven patients scheduled to undergo elective, open biliary tract surgery. INTERVENTIONS: The patients were randomly assigned to receive either cefotetan or cefoxitin in a ratio of 2:1; 76 patients received cefotetan and 35 received cefoxitin. MAIN OUTCOME MEASURES: Wound infection as defined by the Centers for Disease Control and Prevention and by clinical evaluation, adverse events and laboratory parameters. RESULTS: Two incisional wound infections were reported by patients in the cefotetan group, for an overall infection rate of 1.8% (2 of 111). No significant differences were found in the failure rate or in any other indicator of efficacy. The incidence of adverse events for cefotetan (12.6%) was not statistically different from that for cefoxitin (10.4%), and none of the 16 adverse events in the cefotetan group and 5 in the cefoxitin group was serious or severe. Only one event (rash) was possibly related to the study drugs. Several hematologic and biochemical parameters were found to be normal preoperatively and abnormal postoperatively, but no relation was found between these variations and the study drugs. These changes were mainly attributable to the operation. CONCLUSION: Cefotetan was found to be effective and comparable to cefoxitin, both in safety and in reducing the incidence of infection after elective, open biliary tract surgery.

Necrotizing soft-tissue infections.

Necrotizing soft-tissue infections have been widely recognized for over a century, but they remain a challenging problem in clinical infectious disease. Patterns of disease are clearly apparent, but most are polymicrobial and derive increased virulence from synergy between bacteria. Early recognition and prompt surgical drainage are the keys to successful treatment. Edema extending beyond the area of erythema, skin vesicles, crepitus or air in the subcutaneous tissues, and absence of lymphangitis and lymphadenitis are markers of necrotizing infections, particularly when they occur in patients with serious underlying disease. Empiric broad-spectrum antibiotics, prophylactic heparin, and nutritional therapy are important adjuncts to aggressive "stepwise" surgical debridement. A knowledge of patterns of disease can aid in fine-tuning treatment to decrease morbidity.

Efficacy and distribution of single-dose preoperative antibiotic prophylaxis in high-risk gastroduodenal surgery.

Although a single preoperative dose of antibiotic is now the accepted means of preventing postoperative surgical infection, the method has not been investigated adequately. In patients at high risk of infection who underwent gastroduodenal operations, the authors compared single-dose prophylaxis by intravenous cefotaxime (26 patients) with short-course perioperative prophylaxis (27 patients). No wound infection occurred, but in one patient in each group a subphrenic abscess developed after leakage at the anastomosis. The half-life of cefotaxime (1.23 +/- 0.12 hours) and its apparent volume of distribution (16.7 +/- 2.6 L/1.73 m2 resulted in perioperative levels of the antibiotic in blood (34.76 +/- 4.21 micrograms/mL), gastric mucosa (32.04 +/- 5.22 micrograms/mL) and subcutaneous fat (24.98 +/- 5.89 micrograms/mL) more than twice the usual minimal inhibitory concentration of the drug for organisms grown from the stomach contents and wound fat. These clinical and pharmacologic findings validate the efficacy of a single preoperative intravenous dose of the antibiotic in preventing postoperative infection in high-risk patients who undergo gastroduodenal surgery.

Simple elective cholecystectomy: to drain or not.

We performed a large single-center prospective randomized controlled study to assess the role of peritoneal drainage in simple elective cholecystectomy. In 248 patients, drains were omitted; 122 patients had closed suction drains and 124 had Penrose drains. There were no deaths, and no patient required reoperation or drainage of a subhepatic collection. Wound infections occurred in eight patients with drains and in six patients without. Most infections were staphylococcal. Postoperative pulmonary complications and hospital stays were similar in patients with and without drains. Statistical analysis of the 10 available prospective controlled randomized studies (1,920 patients) by the method of odds ratios supported our findings. Simple elective cholecystectomy is safe without peritoneal drainage, but short-term drains do not increase morbidity.

Is neomycin necessary for bowel preparation in surgery of the colon? Oral neomycin plus erythromycin versus erythromycin-metronidazole.

In 132 patients who underwent elective surgery of the colon, the value of bowel preparation with a conventional oral antibiotic preparation of neomycin-erythromycin (N-E) was compared with erythromycin-metronidazole (E-M). Of 125 patients who were available for assessment, 61 received N-E and 64 E-M. The two groups were evenly matched. Two wound infections occurred in patients receiving E-M, neither due to anaerobic bacteria, but seven wound infections developed in patients given N-E (p = 0.057), five of them caused by anaerobic bacteria. Anaerobic bacteria of the colon are the dominant cause of postoperative wound infection in elective surgery of the colon. Adequate antibiotic preparation directed against these bacteria makes the use of neomycin unnecessary.

Natural history of vertical abdominal parietal closure: Prolene versus Dexon.

The long-term outcome of laparotomy incisions after mass closure (taking large tissue bites through all layers) with continuous polypropylene (Prolene) in 95 patients or interrupted polyglycolic acid (Dexon) sutures in 105 patients was compared by randomized prospective study. Of the 200 patients, 194 incisions were median and 2 were paramedian (4 patients were excluded). There was one wound dehiscence (0.51%) due to slippage of a polypropylene knot. At 5-year follow-up, 4 hernias were found in incisions repaired with polypropylene, compared with 11 in the polyglycolic acid group; 10 of the 11 occurred after the first year (p = 0.01). Wound infections were slightly more frequent in patients whose incision was closed with polypropylene. Only two hernias in each group occurred in patients who had had wound infections. Polypropylene and polyglycolic acid both allow rapid and secure closure of vertical laparotomy incisions, but late herniation is more common when polyglycolic acid sutures are used.

Cephalosporin therapy in intraabdominal infections. A multicenter randomized, comparative study of cefotetan, moxalactam, and cefoxitin.

Three broad-spectrum cephalosporins (cefotetan, moxalactam, and cefoxitin) proved effective in this randomized, prospective trial for treatment of 303 surgical patients with moderately severe regional peritonitis.

Comparative study of cefotetan and cefoxitin in the treatment of intra-abdominal infections.

One hundred eighty-eight patients were enrolled in a multicenter, randomized clinical trial to compare the safety and effectiveness of 1 to 2 gm cefotetan every 12 hours with those of 1 to 2 gm cefoxitin every 6 hours in patients with intra-abdominal infections. Most of the infections were community acquired, were associated with gastrointestinal tract perforation, and were caused by both anaerobic and aerobic bacteria. The median duration of therapy was 6 days for each group. The clinical response rate for the 95 evaluable patients in the cefotetan group was 98%, and that for the 43 evaluable patients in the cefoxitin group was 95%. Bacteriologically, 97% of the 58 evaluable patients in the cefotetan group and 89% of the 27 evaluable patients in the cefoxitin group had a satisfactory or presumed satisfactory response; two patients in the cefotetan group and three in the cefoxitin group were considered bacteriologic failures. Cefotetan was as effective as cefoxitin in eradicating Bacteroides fragilis and other species of Bacteroides, Clostridium sp., and gram-negative bacilli. The incidence of treatment-related adverse reactions for cefotetan (27%) was not statistically different from that for cefoxitin (17%). No clinically significant differences were detected between the treatment groups in changes in the results of clinical laboratory tests performed before and after treatment; a decrease in hematocrit among the cefotetan group was statistically greater (p = 0.04) than that for the cefoxitin group, and a decrease in serum creatinine level for the cefoxitin group was greater than that for the cefotetan group (p = 0.02). Cefotetan may represent an effective, safe, and cost-saving alternative to cefoxitin for the prompt treatment of community-acquired intra-abdominal infections.

Biliary bacteria, antibiotic use, and wound infection in surgery of the gallbladder and common bile duct.

That clinical risk groups predict postoperative infection in biliary operations has recently been challenged. To reevaluate the risk of infection, we studied 215 patients stratified by clinical risk factors. Of 100 patients having simple "low-risk" cholecystectomy, 11 had positive bile cultures (90% pure), and one with sterile bile got a staphylococcal wound infection (WI). Among 92 "high-risk" patients with acute cholecystitis, obstructive jaundice, or choledochal stones, 42 had positive bile cultures (44% pure, 12% anaerobes). One of 52 patients who received preoperative cefazolin got a staphylococcal WI, but ten of 40 patients without antibiotic therapy developed WIs, nine caused by organisms that also grew from the bile. Of 23 patients with obstructive cholangitis, 22 had positive bile cultures (88% mixed, 23% anaerobes). Despite antibiotic therapy, four developed WIs caused by these organisms. The concept of clinical risk factors is validated.

The correlation between carotid plaque ulceration and cerebral infarction seen on CT scan.

The purpose of the study was to determine the association between cerebral infarction seen on CT scan and macroscopic ulceration of atheromatous carotid plaques in patients undergoing carotid endarterectomy. Following carotid endarterectomy in 65 patients, specimens were examined for the presence of ulceration without knowing the result of the preoperative CT brain scan. The 65 patients thus investigated underwent 68 carotid endarterectomies: 36 for a history of transient ischemic attacks (TIAs), 13 for amaurosis fugax, and six for prior strokes; 13 asymptomatic patients had prophylactic carotid endarterectomy prior to coronary bypass. A macroscopic ulcer was present in 42 specimens. Twenty-six (62%) of the patients with ulceration had one or more ipsilateral cerebral infarcts on CT scan. Only two (8%) of the 26 patients without an ulcer had cerebral infarcts. Of the 36 patients who presented with TIAs, 26 (72%) had carotid plaque ulcers and 23 (88%) of these had cerebral infarcts on CT scan also. In contrast, only three of 13 asymptomatic patients had plaque ulcers and only one of these had a cerebral infarct. There is a high incidence of cerebral infarction seen on CT scan in patients presenting with TIAs. These infarcts occur predominantly in patients with ulcerated atheromatous carotid lesions.

Knitted polypropylene (Marlex) mesh in the repair of incisional hernias.

In 50 consecutive patients, large incisional hernias or those difficult to manage were repaired by suture imbrication of the hernial sac and extrafascial onlay fixation of Marlex mesh. Seromas developed in three and wound infection in two. The use of closed suction drains for all patients and antibiotic prophylaxis before and after operation for patients with antecedent wound infections may prevent these complications. In the follow-up period (mean of 2.6 years), lateral recurrence of the hernias occurred in three patients, but there has been no recurrence in the last 2 years. The method of repair is simple and effective.

A single preoperative dose of cefazolin prevents postoperative sepsis in high-risk biliary surgery.

To test the ability of cefazolin, given in a single dose preoperatively, to prevent infection in high-risk patients after biliary tract surgery, the authors conducted a double-blind, prospective, randomized, controlled study. Of 92 patients operated on for acute cholecystitis or bile-duct disease, 46 were given 2 g of cefazolin intravenously before operation. Bile was contaminated with bacteria in 36% to 50% of patients with acute cholecystitis, obstructive jaundice, bile-duct disease without jaundice, or over 50 years old compared with only 5% of patients with chronic cholecystitis or under 50 years of age. Postoperative sepsis was eight times more frequent in patients with contaminated bile than in those without. Only 1 patient who received cefazolin had a wound infection, but 9 of the 46 patients in the control group did. The bacteria causing wound sepsis were similar to those in the contaminated bile. The authors conclude that a single dose of cefazolin given intravenously before operation provides effective prophylaxis against infection in high-risk biliary tract surgery.