Structure guided mutagenesis of Henipavirus Receptor Binding Proteins reveals molecular determinants of receptor usage and antibody binding epitopes.

Nipah virus (NiV) is a highly lethal, zoonotic henipavirus (HNV) that causes respiratory and neurological signs and symptoms in humans. Similar to other paramyxoviruses, HNVs mediate entry into host cells through the concerted actions of two surface glycoproteins: a receptor binding protein (RBP) that mediates attachment and a fusion glycoprotein (F) that triggers fusion in an RBP-dependent manner. NiV uses ephrin-B2 (EFNB2) and ephrin-B3 (EFNB3) as entry receptors. Ghana virus (GhV), a novel HNV identified in a Ghanaian bat, use EFNB2 but not EFNB3. In this study, we employ a structure-informed approach to identify receptor interfacing residues and systematically introduce GhV-RBP residues into a NiV-RBP backbone to uncover the molecular determinants of EFNB3 usage. We reveal two regions that severely impair EFNB3 binding by NiV-RBP and EFNB3-mediated entry by NiV pseudotyped viral particles. Further analyses uncovered two point mutations (NiVN557SGhV and NiVY581TGhV) pivotal for this phenotype. Moreover, we identify NiV interaction with Y120 of EFNB3 as important for usage of this receptor. Beyond these EFNB3-related findings, we reveal two domains that restrict GhV binding of EFNB2, identify the HNV-head as an immunodominant target for polyclonal and monoclonal antibodies, and describe putative epitopes for GhV and NiV-specific monoclonal antibodies. Cumulatively, the work presented here generates useful reagents and tools that shed insight to residues important for NiV usage of EFNB3, reveals regions critical for GhV binding of EFNB2, and describes putative HNV antibody binding epitopes.

The evolutionary dynamics of influenza A virus adaptation to mammalian hosts.

Few questions on infectious disease are more important than understanding how and why avian influenza A viruses successfully emerge in mammalian populations, yet little is known about the rate and nature of the virus' genetic adaptation in new hosts. Here, we measure, for the first time, the genomic rate of adaptive evolution of swine influenza viruses (SwIV) that originated in birds. By using a curated dataset of more than 24 000 human and swine influenza gene sequences, including 41 newly characterized genomes, we reconstructed the adaptive dynamics of three major SwIV lineages (Eurasian, EA; classical swine, CS; triple reassortant, TR). We found that, following the transfer of the EA lineage from birds to swine in the late 1970s, EA virus genes have undergone substantially faster adaptive evolution than those of the CS lineage, which had circulated among swine for decades. Further, the adaptation rates of the EA lineage antigenic haemagglutinin and neuraminidase genes were unexpectedly high and similar to those observed in human influenza A. We show that the successful establishment of avian influenza viruses in swine is associated with raised adaptive evolution across the entire genome for many years after zoonosis, reflecting the contribution of multiple mutations to the coordinated optimization of viral fitness in a new environment. This dynamics is replicated independently in the polymerase genes of the TR lineage, which established in swine following separate transmission from non-swine hosts.

The limited role of total parenteral nutrition in the management of pancreatic pseudocyst.

Total parenteral nutrition (TPN) for the nonoperative treatment of acute pancreatic pseudocyst has been of hypothetical benefit. We reviewed pseudocyst hospital admissions in 40 patients treated with TPN who had serial imaging studies. The mean cyst size was 7.4 cm on presentation, decreasing to 5.6 cm after nonoperative treatment with TPN (mean 32.5 days). After a nonoperative period, 68 per cent of cysts regressed, completely in 14 per cent, partially in 54 per cent. Except for a patient with cyst-related obstructive jaundice, there were no complicated pseudocysts. Only 12 (28%) patients underwent cyst drainage. Fifteen patients (35%) sustained catheter-related complication, which included sepsis (26%), pneumothorax (9%), hydropneumothorax (2%), and septic right atrial thrombosis (2%), in the course of hospitalization. The majority of TPN-treated patients had a clinical and radiographic regression of their pseudocyst. However, the increased risk of catheter-related complications in this group suggests that this therapy should be limited to patients who are unable to sustain enteral nutrition.

Buprenorphine versus morphine for patient-controlled analgesia after cholecystectomy.

Buprenorphine is an opioid agonist-antagonist that has emerged as an option for postoperative analgesia. We compared the postoperative hospital course of patients undergoing open cholecystectomy who received buprenorphine hydrochloride with those who received morphine sulfate. Patients in both groups administered the analgesic using a patient-controlled analgesia infusion device. Comparison of the two groups demonstrated no difference with respect to clinical indicators of intestinal motility, visual analog pain scores and hospitalization period. Postoperative nausea occurred more frequently in the buprenorphine group, but the difference was not significant. We concluded that the patient-controlled analgesia device is a valuable tool for comparing different analgesics. Both analgesics tested provide adequate analgesia with a similar postoperative course.

Evaluation of occlusion, trauma, and dental anomalies in African-American children of metropolitan Headstart programs.

493 African-American children between the ages of three and four years were examined for evaluation of molar occlusion with frequency of anterior and posterior crossbite, fractured and/or darkened teeth from trauma and dental anomalies in the primary dentition. Overall results from both age groups revealed 90% had a mesial step, 8% a flush and 2% a distal step molar occlusion. Crossbite, either anterior or posterior, occurred in 12% of all children examined. Posterior crossbite was seen in 7% and anterior crossbite in 5%. Anterior openbite was seen in 8% of the children. Trauma to the primary dentition occurred in 23% of the children, 16% as fractured and 7% as discolored teeth. The most frequently involved teeth were the maxillary primary central incisors. Fused primary teeth were observed in two children. There were no congenitally missing primary teeth and only one supernumerary maxillary primary lateral incisor was observed.

Gastrostomy: operative or nonoperative?

Percutaneous endoscopic gastrostomy (PEG) is clearly better than operative gastrostomy performed under general anesthesia. Whether or not PEG offers any significant advantage over operative gastrostomy performed using local anesthesia remains to be proved. Operative gastrotomy performed with local anesthesia seems comparable to nonoperative techniques.

A prospective study of patient-controlled analgesia. Impact on overall hospital course.

Previous studies have shown that patient-controlled analgesia (PCA) provides effective pain control in the postoperative patient. To determine the impact of PCA technology on the overall hospital course, we designed a randomized controlled study comparing patients receiving analgesia using PCA infusion (Abbott Lifecare, Abbott Laboratories; Chicago, IL) with patients receiving analgesia by traditional intramuscular or intravenous methods. All patients had undergone elective cholecystectomy. Sixty-nine patients completed the study, 35 received traditional postoperative analgesia, and 34 received analgesia using the PCA infuser. Comparison of both groups demonstrated no significant difference in postoperative bowel activity with both groups receiving liquids on the first postoperative day. There was no significant difference between the two groups with respect to postoperative length of stay (3.4 days for PCA vs 3.6 days for traditional). Patients demonstrated a wide range of analgesic requirement in the first 24 hours but the average of the total analgesic required was higher in the PCA group (average, 29.5 mg) than the traditional group (22.8 mg). Urinary complications occurred more commonly in the group of patients receiving traditional analgesia than in the group of patients receiving analgesia with the PCA device. When compared with patients receiving analgesia by traditional methods, patients receiving the PCA infusion required more analgesia with fewer urinary complications and similar postoperative length of stay.

Role of highly selective vagotomy and duodenoplasty in the treatment of postbulbar duodenal obstruction.

The indications for highly selective vagotomy have expanded in recent years, with the technique being applied to selected cases of perforation and bleeding. Its use in obstruction is controversial, but two options are available for managing the stenotic pylorus or duodenum: dilatation or duodenoplasty. The latter choice requires that the stenosis be located in the postbulbar area. Since 1981, we have managed 15 patients with postbulbar stenosis by means of highly selective vagotomy and duodenoplasty. All patients had a previous history of ulcer disease, and vomiting was a consistent symptom. All patients were referred for surgery, 10 by a gastroenterologist. There was no operative mortality or procedure-related morbidity. Two patients have been lost to follow-up. Both were classified as Visick I and had normal endoscopic results at their last visit. The remaining 13 patients have all been followed very recently. Twelve patients (92%) are currently classified as Visick I or II. One patient (Visick IV), who was essentially asymptomatic, was found to have a recurrent ulcer on endoscopy. Endoscopic (11 patients) or radiographic (1 patient) patency of the duodenoplasty has been demonstrated in 12 patients. Highly selective vagotomy and duodenoplasty should be a surgical consideration when the pathologic anatomy of the duodenum lends itself to that choice.

Percutaneous endoscopic gastrostomy. Do surgeons and gastroenterologists get the same results?

Numerous investigators have reported the safety, cost effectiveness, and low morbidity and mortality of percutaneous endoscopic gastrostomy (PEG) but not studies compare the results of gastroenterologists and surgeons performing PEG. In a retrospective review of PEG performed at our institution, morbidity and mortality were compared between these two groups. The procedure was performed by either the surgical service (n = 49) or gastroenterology service (n = 51). One hundred PEGs were successfully placed in 92 patients. Three placement failures occurred in the gastroenterology group. Major complications were defined as conditions requiring operative intervention or resulting in death. Minor complications, using a defined list (13 different complications), were those not serious or life-threatening, which were managed medically or resolved without treatment. Twenty-nine minor (17 patients) complications and 3 major (3 patients) complications occurred in the gastroenterology group. Thirteen minor (11 patients) complications and 4 major (4 patients) complications occurred in the surgery group. Overall 30-day mortality was 14 per cent (13 patients), two of which were probably procedure-related in the gastroenterology group. In both groups, there was no difference in the numbers of patients who had complications (P greater than 0.05). The complication rate (numbers of complications/number of patients) doubled in the gastroenterology group compared with the surgery group for minor (P less than 0.04) and total complications (minor and major--P less than 0.06). Since PEG is a procedure frequently performed by gastroenterologists, it is imperative that surgeons, particularly those not performing endoscopy, be aware of the potential morbidity associated with PEG.

Endoscopy of the small intestine.

For the patient and the clinician, it is well that small-bowel diseases are unusual, as our ability to access this area remains limited. Frequently, all of the diagnostic and therapeutic modalities of radiology, endoscopy, and surgery are required for successful resolution of a given problem. Because management of bleeding from a small-bowel source usually will involve the surgeon at some point, it is mandatory that the best "road map" be obtained prior to exploration. If a small-bowel source is suspected after a negative endoscopic evaluation of the esophagus, stomach, duodenum, and colon, then the clinician must decide which radiographic and endoscopic examination is most appropriate. If bleeding is slow or intermittent, push-type enteroscopy to evaluate the proximal jejunum will have an expected diagnostic discovery rate of about 30 per cent. A stiffening over-tube or internal cable should result in deeper passage of the instrument and a potentially greater yield. Retrograde ileoscopy should be a part of every colonoscopy done for occult bleeding. If endoscopy does not identify a bleeding source, then a detailed barium study of the small bowel using an enteroclysis double-contrast technique will discover more pathology than a standard small-bowel-follow-through. Because sonde-type enteroscopes are not readily available, the clinician must decide at this point whether to refer the patient to an enteroscopist or consider surgery and intraoperative endoscopy. If a bleeding source has been found, then intraoperative endoscopy can localize lesions for specific resection. If the pathology remains obscure, intraoperative endoscopy will have a discovery rate of about 70 per cent. For more active hemorrhage, a bleeding scan with 99mTc-labeled red blood cells can confirm that blood loss is continuing and also will guide the angiographer toward a more directed study, thus decreasing the contrast material load for the patient. If a bleeding source can be identified angiographically, a short course of vasopressin infusion to convert the need for surgical intervention to a more elective situation would be beneficial to the patient. Intraoperative endoscopy under urgent conditions is more difficult, because luminal blood must be lavaged or cleared for a proper examination. Many times, however, intraoperative endoscopy can "surround" a segment of intestine by identifying areas that are clearly normal.

A comparison of monobactam antibiotics in surgical infections.

The introduction of gentamicin almost 20 years ago provided an effective option for the treatment of gram-negative bacillary infections. During the past few years, the availability of aztreonam (a monobactam), imipenem (a carbapenem), and newer cephalosporins within vitro activities comparable with aminoglycosides against many gram-negative bacilli, has stimulated a reassessment of the role of aminoglycosides in treating these infections. When determining the role of new antimicrobials as potential replacements for more established agents, the clinical focus should be on three factors: comparative efficacy, safety, and cost. Consideration of cost is relevant only when efficacy and safety are equivalent. Other factors, such as comparative in vitro antimicrobial activity, pharmacokinetics, and effect on normal flora can also influence the selection of an antimicrobial regimen. A new class of antimicrobials, the monobactams, is the focus of this review. The only member of this class currently in clinical use is aztreonam. A comparison with aminoglycosides is particularly relevant because aztreonam is active against aerobic gram-negative bacilli. This review will discuss the acknowledged concerns with aminoglycoside use and compare the characteristics of aztreonam and currently marketed aminoglycosides.

Single-dose cefmetazole versus multiple dose cefoxitin for prophylaxis in abdominal surgery.

One hundred and ninety-five patients undergoing abdominal surgical procedures completed a multicentre, randomized, open-label study comparing the safety and efficacy of cefmetazole and cefoxitin for the prevention of postoperative wound infection. Cefmetazole was administered iv in a single 2 g dose given within 90 min of the operation. Cefoxitin was administered in a single 2 g, similarly timed, preoperative dose and two additional doses given at 6 h intervals after surgery. For operations that exceeded 2-4 h duration an additional dose of each agent was administered. Patients undergoing colorectal operations received oral neomycin and erythromycin as bowel preparation. Colorectal operations were performed most frequently (49% of patients) followed by cholecystectomies (26%) and gastroduodenal procedures (21%). The operative site infection rate was 6.5% for cefmetazole and 7.7% for cefoxitin (P greater than 0.05). Serious drug related adverse effects were not observed. This study demonstrates that administration of single-dose cefmetazole is as effective as a standard three dose regimen of cefoxitin for prophylaxis with abdominal operations.

Comparative intraoperative concentrations of two cephalosporins with activity against anaerobic bacteria.

We determined the intraoperative concentrations of cefmetazole and cefoxitin in serum and muscle from the wound of 30 patients who were undergoing cholecystectomies. The study employed an open-label design in which all patients randomly received cefoxitin sodium (30 mg/kg) or cefmetazole sodium (15 or 30 mg/kg) intravenously with the induction of anesthesia. Total serum and wound-muscle concentrations achieved with cefmetazole 30 mg/kg were significantly greater than those achieved with a similar dose of cefoxitin. Cefmetazole in a 15 mg/kg dose was comparable with cefoxitin 30 mg/kg in achieved concentrations. The elimination half-life for cefoxitin was much shorter than that for cefmetazole (41 min v. 64-68 min, respectively) and this relates to a shorter duration of action for the former. The choice of agent for surgical prophylaxis should incorporate factors relating to drug pharmacokinetic properties as well as microbiological factors.

Intraoperative endoscopy of the gastrointestinal tract: clinical necessity or lack of preoperative preparation?

Intraoperative gastrointestinal endoscopy is an evolving technique that has received limited attention in the literature through case and small series reports. This literature does contain some papers in which the method was employed instead of conventional endoscopy, but, in general, intraoperative endoscopy has been effectively used as an aid to the surgeon to locate pathology not otherwise detectable and to enhance diagnosis and therapy at laparotomy. The procedure will not be required often, but when used, has the potential to be of as much service to the surgeon as a scalpel or retractor. As more surgeons are being trained in gastrointestinal endoscopy, the indications and uses will surely expand.

Endoscopically assisted nasojejunal feeding tube placement.

Enteral nutrition is best delivered via a small bore feeding tube whose tip lies in the proximal jejunum. A major obstacle to tube placement is the lack of a reliable means of assuring passage through the pylorus. A simple, quick method of tube placement using endoscopic assistance that was successful in 18 of 20 (90%) attempts is described.

Lower gastrointestinal bleeding. A systematic approach to classification and management.

Early classification of lower gastrointestinal bleeding as occult, minor overt, or major overt allows a practical approach to evaluation and management. Localization of the bleeding site is the next step. In occult and minor overt bleeding, the cause can usually be determined from results of conventional diagnostic tests; however, angiography and even intraoperative endoscopy may be necessary in some particularly difficult cases. In contrast, major overt bleeding may only allow time for angiographic localization before surgery. Using this approach, the primary care physician can successfully manage most patients with lower gastrointestinal bleeding.

Selective intraoperative cholangiography. A case for its use on an anatomic basis.

The routine use of intraoperative cholangiography has vastly improved the results of common duct exploration by reducing the number of negative explorations. The controversy surrounding the use of routine versus selective intraoperative cholangiography has centered on the incidence of unsuspected common-duct stones. A prospective study was designed to examine both preoperative clinical data and intraoperative anatomical information to determine criteria that would identify patients who would not require cholangiography. One hundred consecutive patients undergoing cholecystectomy were included in the study. When considering patients without preoperative clinical data suspicious for common duct stones three anatomical conditions were identified in which common duct stones would not be present: cystic duct less than 3 mm; smallest stone size greater than 6 mm; a single stone. Using intraoperative criteria as a basis for cholangiography, 44 per cent of patients without clinical suspicion of common duct stones would be spared an intraoperative cholangiogram. It is the authors' opinion that the addition of anatomic findings to preoperative clinical data can further reduce or eliminate the risk of unsuspected stones while sparing a large number of patients the risk and expense of routine intraoperative cholangiography and possible negative duct exploration.